Key Questions About the Triune God
Lesson Focus: This lesson is about the central Christian doctrine that God is Trinity – one God existing eternally in three Persons. Drawing on selected Bible passages, the lesson explores answers to three key questions about the one God who exists in three Persons.
How Do We Know God is One in Three?: Matthew 3:16-17.
 And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him;  and behold, a voice from heaven said, "This is my beloved Son, with whom I am well pleased." [ESV]
Matthew does not describe the baptism, but takes up his narrative from the time when it was completed. It is not easy to see what is meant by the opening of the heavens, but we should probably think that for a short time the barrier between this world and heaven was set aside so that there could be some form of intercourse between the two. The sight of the opened heavens and the visible manifestation of the Spirit would have been an encouragement to Jesus. Whether other people shared in the experience or not was apparently not so important to Matthew, and he leaves us to puzzle about it. Jesus saw the Spirit of God descending like a dove and coming to rest on him. The meaning of the symbolism of the dove is unclear. There is no evidence that at the time of Jesus the dove was a symbol of the Holy Spirit. But the dove was sometimes a symbol for Israel, and it is possible that this is in mind here. If so, Jesus is seen as the true, ideal Israelite when He receives the Spirit of God at the threshold of His public ministry. The voice from heaven is God’s and testifies that God Himself has broken silence and is again revealing Himself to men – a clear sign of the dawning of the Messianic age [see 17:5; John 12:28]. This saying by God reflects Isaiah 42:1: Behold my servant, whom I uphold, my chosen, in whom my soul delights; I have put my Spirit upon him; he will bring forth justice to the nations. These words from heaven link Jesus with the Suffering Servant at the very beginning of His ministry. Jesus has already been set forth as the true Israel to which actual Israel was pointing and as such God’s Son [see 2:15]; now the heavenly witness confirms the link. The Spirit’s descent in verse 16 needs to be understood in the light of verse 17. The Spirit is poured out on the servant in Isaiah 42:1-4, to which verse 17 alludes. This outpouring does not change Jesus’ status (He was the Son before this) or assign Him new rights. Rather it identifies Him as the Promised Servant and Son and marks the beginning of His public ministry.
How Can We Better Understand God’s Mysterious Nature?: 1 Corinthians 2:12-13..
 Now we have received not the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God.  And we impart this in words not taught by human wisdom but taught by the Spirit, interpreting spiritual truths to those who are spiritual.
Paul shifts his focus to the means by which God reveals heavenly truth that is naturally unknowable. Human creatures do not have access to heavenly truth and do not even have the grammar or vocabulary for them until it is graciously bestowed by God’s Spirit. Rather than searching human hearts, the Spirit, as pictured by Paul, penetrates and discloses the depths of God which refer to what God has foreordained [2:7] and prepared [2:9], the divine plan for human redemption [see Romans 11:33]. Only God’s Spirit apprehends God’s plans and purposes, and only God’s Spirit can link God and humans together. Paul’s intention is to draw a thick and heavy line between things human and divine and to place the things of God squarely outside the limits of human knowing. That line is crossed only by the divine Spirit. The believers’ prior reception of the Spirit is foundational to Paul’s argument and is taken for granted. Those who receive and experience divine revelation must have already received the Spirit. Spiritual persons are those Christians in whom the Spirit has really become the fundamental power of life. But Paul’s main point is that what derives from this world cannot bridge the gap to apprehend God. Paul’s statement in 2:13 recalls what he argues in 2:4. His preaching was not with the persuasiveness of wisdom but with the demonstration of the Spirit and power. His teaching was not human invention but words taught by the Spirit. The concluding phrase, interpreting spiritual truths to those who are spiritual, emphasizes that the apostolic teaching was entirely dependent upon the Spirit teaching the apostles spiritual truth with spiritual words and only those who have the Spirit can understand their teaching. Thus this verse is a strong indication of the divine inspiration of Scripture.
Why is the Concept of God as Trinity Important?: Ephesians 1:3-14.
 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places,  even as he chose us in him before the foundation of the world, that we should be holy and blameless before him. In love  he predestined us for adoption through Jesus Christ, according to the purpose of his will,  to the praise of his glorious grace, with which he has blessed us in the Beloved.  In him we have redemption through his blood, the forgiveness of our trespasses, according to the riches of his grace,  which he lavished upon us, in all wisdom and insight  making known to us the mystery of his will, according to his purpose, which he set forth in Christ  as a plan for the fullness of time, to unite all things in him, things in heaven and things on earth.  In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will,  so that we who were the first to hope in Christ might be to the praise of his glory.  In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit,  who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory. [ESV]
[3-4] Paul begins by blessing God for showering us with every spiritual blessing. With every spiritual blessing is the first of three phrases commencing with the preposition in or with, which modifies the verb blessed. These expressions describe in different ways the content of God’s blessings. Everything that Christians have received through God’s saving act in Christ is comprehensively summarized in the expression every spiritual blessing which refers to those blessings that pertain to the life of the Spirit. The nature of these gracious gifts is made plain in verses 4-14, and include election to holiness, adoption as God’s sons and daughters, redemption and forgiveness, a knowledge of God’s gracious plan to sum up all things in Christ, the gift of the Spirit, and the hope of glory. The recipients of these gracious gifts of God are us which refers to the people of God who have received His mighty salvation. The blessings of the heavenly realms which believers receive are in Christ. This phrase signifies that God’s gracious gifts come not only through the agency of Christ but also because the recipients are incorporated in Him who is Himself in the heavenly realm. The phrase in Christ, together with its variants ‘in him’ and ‘in whom’, occurs eleven times in this paragraph. It is in him that God has chosen us in eternity [3-4]. The Father has bestowed His grace upon us in the Beloved , so that we now have redemption and the forgiveness of sins in him . In Christ the first Jewish believers were chosen to become God’s people [11-12], while Gentile believers were also included in him and were sealed as belonging to Him by the Holy Spirit [13-14]. Significantly, it is in Christ that God has set forth His plan to unite all things in him or under His headship [9-10]. The sweeping blessings of verse 3, which are said to be in Christ are now amplified through the even as clause of verse 4 and the following verses. The great theme of divine election is the first to be introduced as Paul’s mind reaches back before creation, before time began, into eternity in which only God Himself existed. Election is one of a variety of motifs found in this magnificent paragraph that describe different facets of God’s gracious, saving purposes: note the language of predestination [5,11], purpose [5,9,11], will [5,9,11], mystery , plan or counsel [10,11]. The object of God’s choice is us, that is, believers, who now belong to the people of God. But our election is always and only in him (Christ). He is the foundation and origin: all that is involved in election and its fruits depends on Him. That choice in Christ was made in eternity, before the foundation of the world. To say that election took place before creation indicates that God’s choice was due to His own free decision and love, which were not dependent on temporal circumstances or human merit. The reasons for His election were rooted in the depths of His gracious, sovereign nature. The goal for which God chose His people in Christ is that we should be holy and blameless before him. Election does bring privilege, but it also carries with it responsibility. The divine purpose in our election was not simply to repair the damage done by sin but also to fulfill God’s original intention for humankind, namely, to create for Himself a people perfectly conformed to the likeness of his Son. The two adjectives holy and blameless refer to ethical holiness and freedom from moral blemish. Before him points to the time when we will stand before God in His presence. But this is not to suggest that there is consequently no concern for holiness and blamelessness in the here and now. Holiness is meant to be progressively wrought within the lives of believers on earth by the Spirit, and will be consummated in glory at the parousia. It is not certain whether the words in love should be attached to what precedes or to what follows. If it is the former, then it adds a specific quality to holiness and blamelessness: the purpose of God is that His people should be marked by holiness and blamelessness, coupled with love. If it is to the latter, then in love expresses God’s attitude to His people when He foreordained them for adoption into His family.
[5-6] The verb predestined (or foreordain), which appears six times in the New Testament, is used exclusively of God and serves to emphasize His sole initiative and authority in our salvation. Predestination is for a God-designed purpose, in this instance, adoption, which signifies entry to a privileged position. Being adopted into God’s family is an incredible privilege, because those now able to call upon Him as Father were at one time sons of disobedience and children of wrath [2:2-3]. This personal relationship is made possible only through Jesus Christ, a highly significant expression which points to His agency. It is only through the work of God’s Son, the Beloved, that believers can be adopted as sons. The basis or standard of God’s action in foreordaining us to be His children is spelled out in the compound phrase according to the purpose of his will. The word the ESV translates as purpose also means ‘pleasure’. The word signifies not simply the purpose of God but also the delight that He takes in His plans. The preposition according to indicates the norm or standard, showing that His choosing many to come into a special relationship with Himself was in keeping with what He delighted to do and with His saving plan. Consequently, as men and women break out in praise [3,6,12,14], their pleasure in God is a response to His delight in doing good to them. It was God’s intention that His free and glad choice of men and women to be His sons and daughters might redound to the praise of his glorious grace. Grace is a key theme in Ephesians: it is through grace that we are saved [2:5,8], the forgiveness of our trespasses is in accordance with the riches of divine grace [1:7], while Paul’s receiving the gospel, his calling to minister to the Gentiles, and his ability to fulfill his missionary task from beginning to end were due solely to the grace of God. This grace is described as glorious. Glory is used often in the Bible to describe the manifestation of God’s presence with His people; it refers to His saving presence. To say that God’s grace is truly glorious means that it reflects His glory, His revealed character, and is therefore worthy of our praise. If God’s choice of men and women to be His sons and daughters arises from His grace, then the final goal of this divine predestination is that it might resound to the praise of that glorious grace. The last half of verse 6 stresses that it is in the Beloved, Jesus Christ, that God has poured out all His grace upon us.
[7-8] Those who praise God for His glorious grace freely given in Christ can rejoice in a deliverance from their trespasses through His sacrificial death on the cross. Redemption, which signifies liberation from imprisonment and bondage, is not simply the object of our future hope, but it is a present possession which has been procured through his blood. This abbreviated expression signifies that Christ’s violent death on the cross as a sacrifice is the means by which our deliverance has been won. It was obtained at very great cost. The redemption in view is equated with the forgiveness of our trespasses, for it involved a rescue from God’s just judgment on our sins. As a result we now have free access to our heavenly Father, knowing that we have been redeemed and forgiven. Significantly, the references to our sin and to the divine redemption and forgiveness are framed by important statements about the grace which God has lavished on us [6b,7c,8a]. The decisive rescue from divine judgment on our trespasses is wholly in keeping with the riches of his grace which he lavished upon us. This statement about the abundance of divine grace has been intensified by means of the noun riches. And the verb lavished with its connotation of wealth and extravagance, make it crystal clear that our redemption is all of grace. Words are hardly adequate to describe the inexhaustible nature of God’s giving. This generous bestowal of God’s grace is accompanied in all wisdom and insight which are mentioned because of their relevance to what follows in verses 9-10.
[9-10] God intended that we should understand His saving purposes. He therefore lavished His grace upon us in all wisdom and insight by making known to us the mystery of his will. Making known a mystery refers to the disclosure of a previously hidden secret. The mystery of God focuses on salvation through the cross of Jesus Christ. It cannot be understood through human wisdom but comes to be known as God reveals it by His Spirit to those who love him. It is in the effective preaching and teaching of the gospel that the revelation of the mystery takes place [see Eph. 3:8,9; 6:19]. The content of the mystery is to unite all things in him. The word translated unite has the meaning of ‘to bring something to a main point, to summarize’. Thus God is summarizing or bringing together all the various points of His plan in Christ. Christ is the focal point, not simply the means by whom God will restore harmony to the universe. The emphasis is now on a universe that is centered and reunited in Christ. The mystery which God has graciously made known refers to the summing up and bringing together of the fragmented and alienated elements of the universe in Christ as the focal point.
[11-12] The Christ who is at the center of God’s plan to sum up all things in heaven and on earth is also the one in whom we were claimed by God as His portion and designated His beneficiaries. The we here refers to Paul and his fellow Jewish believers. The Gentile readers of the letter are not included in this designation, but are explicitly mentioned in the you of verse 13. Paul picks up his earlier language of predestination and the divine will  and applies it now to those who were the first to hope in Christ being chosen as the Lord’s personal possession. God’s unconditional freedom is stressed, so that whatever He has planned and decided to do will certainly come to pass. The praise of his glory is the object for which those who first hoped in Christ were chosen as the Lord’s portion. The outworking of God’s gracious purposes for His people is for His own glory, and that goal is fulfilled, partially at least, as He is honored in the presence of human beings and angelic powers when men and women, redeemed from sin, live in accordance with His will and display the family likeness which stamps them as His children.
[13-14] Gentile Christians, who are now addressed specifically as you also, were sealed with the Holy Spirit of promise and made His own when they heard the message of truth and received it. Within God’s eternal purpose in Christ Gentile believers were incorporated into the one people of God. Their share in God’s heritage was as complete as those of Jewish birth who first hoped in Christ. Like Jewish believers before them, Gentiles heard the gospel and realized that the salvation of which it spoke was for them too. The apostolic announcement which they heard is called the word of truth, the gospel of your salvation. This word of truth is to be understood against an Old Testament background where God’s word, spoken and revealed to men and women, partakes of His character and is utterly reliable. When the Gentiles believed the gospel, they were sealed with the promised Holy Spirit. The believing and being sealed were two sides of the one event. In speaking of the Holy Spirit as a seal the notions of ownership and protection are in view. In the Old Testament God set a sign on His chosen ones to distinguish them as His own possession and to keep them from destruction. By giving Gentile believers the Spirit, God seals or stamps them as His own now, and He will protect them through the trials and testings of this life until He takes final possession of them on the day of redemption. Paul is making the connection between hearing the gospel, believing, and receiving the Spirit as important elements of the initiation of conversion. The Holy Spirit by whom the Gentiles were sealed when they believed the gospel is now called the deposit or guarantee of our inheritance. Because of the ministry of the Spirit to their hearts and lives, they can begin to enjoy this everlasting possession now. The Spirit received is the first installment and guarantee of the inheritance in the age to come that awaits God’s sons and daughters . The praise of God’s glory was the object for which those who first hoped in Christ were chosen . Now as a climactic parallel to what has preceded, God’s final aim in sealing Gentile believers with the Holy Spirit is joyfully presented as to the praise of his glory. Gentile Christians (you also) have been assigned the same ultimate destination predicated of Jewish believers , for the glory of God is the final aim of the whole unfolding of salvation.
Questions for Discussion:
1. What do you see as the significance of Jesus’ baptism and the events surrounding it?
2. What was Paul’s main point in 1 Corinthians 2:12-13?
3. Ephesians 1:3-14 is one long, complex sentence in the Greek that contains a wealth of biblical doctrine which cannot be explained in depth in just a few pages. But, as an introductory approach, make a list of all the spiritual blessings which Paul gives in these verses. Add to your list what each person of the Trinity is doing concerning making these spiritual blessings a reality to believers. What is the ultimate goal of these spiritual blessings? What must you do in your daily life to make this goal a growing reality in your spiritual journey?
The Gospel According to Matthew, Leon Morris, Eerdmans.
1 Corinthians, David Garland, Baker.
The Letter to the Ephesians, Peter O’Brien, Eerdmans.