We should celebrate the fact that there are many avenues and means for participating in missions, especially as the world is becoming a very complex place for missionaries. One note of caution that we must beware of is the tendency to innovate and improvise with sacred tasks that God has not permitted. This is exactly what happened in the account of Nadab and Abihu, the sons of Aaron the High Priest:
Now Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it and laid incense on it and offered unauthorized fire before the LORD, which he had not commanded them. And fire came out from before the LORD and consumed them, and they died before the LORD. Then Moses said to Aaron, ‘This is what the LORD has said: “Among those who are near me I will be sanctified, and before all the people I will be glorified.”’ And Aaron held his peace (Lev. 10:1-3).
Notice carefully what the text says and does not say. Did Nadab and Abihu offer specific fire that the Lord explicitly told them not to offer? In Exodus 30:8-9 the Lord certainly instructs Aaron to offer regular incense over against some other unauthorized incense. But this record in Leviticus 10:1-3 does not emphasize the fact that they offered fire that God unambiguously prohibited; it underscores, rather, that they offered unauthorized fire that God had not commanded them. In other words, Moses is recording that Nadab and Abihu exceeded what God had mandated. The Lord had told them what to offer. They relaxed, innovated, and improvised. They erred by going beyond the bounds of the Word and not holding fast to the instructions. Jealous for the church to not esteem the Apostles higher than they ought, but rather as trustworthy stewards of the Word, Paul issues a similar New Testament instruction in 1 Corinthians 4:5-6:
Therefore do not pronounce judgment before the time, before the Lord comes, who will bring to light the things now hidden in darkness and will disclose the purposes of the heart. Then each one will receive his commendation from God. I have applied all these things to myself and Apollos for your benefit, brothers, that you may learn by us not to go beyond what is written, that none of you may be puffed up in favor of one against another.
Wisdom applications of this theology of Christian service can apply to missions. This does not mean that we must retrofit our missionary endeavors to imitate exactly the precise descriptions of Paul’s methods, and it does not mean that we cannot develop creative platforms to access hard-to-reach peoples in countries politically and religiously hostile to Christianity. It does mean, however, that we should fearfully heed and faithfully hold fast to the Great Commission passages that mandate the transcultural and timeless requirements of the church’s mission as senders and sent ones. Would that missionary-theologians devote themselves to keeping the missionary commands of Scripture, not going beyond what is written by creatively making biblical imperatives out of theological implications, inferences, or indicatives. Not to overstate the case, it helps to remember that we should avoid what Scripture forbids and obey what it commands. And where it does not speak, we have freedom within the bounds of Scriptural wisdom and theological discernment. Kevin DeYoung and Greg Gilbert make a helpful point:
We are concerned that in our newfound missional zeal we sometimes put hard “oughts” on Christians where there should be inviting “cans”. You ought to do something about human trafficking. You ought to do something about AIDS. You ought to do something about lack of good public education. When you say “ought”, you imply that if the church does not tackle these problems, we are being disobedient. We think it would be better to invite individual Christians, in keeping with their gifts and calling, to try to solve these problems rather than indicting the church for “not caring”.
In missions, creativity is good but not ultimate. We should be thankful that we are not all clones of one single personality, temperament, and background. Frankly, that would be as bland as all having the same voice, accent, and rhythm of speaking. All missionaries uniquely contribute to the Great Commission in ways that God has specially designed. In missions, creativity and innovation are good but not ultimate. Yet, at times the focus on discovering and using one’s passion internationally for God can get a bit bizarre: ‘I have a passion for surfing; the Lord told me to reach Hindu surfers in Bali. . . . I am passionate for mountain climbing; God has called me to start a mountain climbing business in Nepal. . . . I love horses; God wants me to teach animal husbandry to Mongolians.’ These are just a sampling of what I have heard as evidence of God’s call to the mission field. These statements could be improved with more theologically careful and precise language, not confidently claiming that God has said more than what He has said in the Bible and by just describing how He seems to have providentially led.
Lest we overemphasize and confuse individuality with ministry philosophy specifics, we must remember that methodology of missions is never neutral. We will lose the message of Christ crucified as we innovate our methods and standards insofar as they are incompatible with the honor and truth of the message. Casual, pragmatic, and light-hearted methods and standards cheapen an otherworldly, profound message. No king or president on the eve of war or on the morning after the country’s decisive victory would address his nation in a costume, entertaining with levity and originality. The gravity and the good news of taking refuge in his authority would dwindle under the weightlessness of his frivolous methods of delivery.
We all recognize that titles, offices, and ranks matter. An on-duty police officer wields the force of the law by nature of his appointed office. A common citizen cannot claim to be a servant of justice and an enforcer of the law without earning the official approval of the duties and privileges of that office. The same is true for nearly any other duty and office: military special forces, cardiologists, NASA scientists, and university presidents. Though a well-meaning person might claim a certain office, it does not mean they are qualified for that role. Noble aspirations, persistent interest, and unique experiences never qualify anyone to perform brain surgery, establish new laws, judge a criminal, or engage in battle with a foreign enemy. If these are true for temporal offices and duties that pertain only to this life, why do we permit anyone and everyone to ‘do missions’ based upon merely an express interest and compelling desire?
To be sure, people who volunteer for missions mean well and want to make a difference, and this is an admirable desire. And truly, the modern missionary movement of the nineteenth and twentieth centuries, fueled by volunteerism, is one of the most influential movements in world history. As much as we should celebrate the many who willingly made great sacrifices, we must remember that desire for ministry does not equal calling. Paul makes this clear: ‘Certain persons, by swerving from these, have wandered away into vain discussion, desiring to be teachers of the law, without understanding either what they are saying or the things about which they make confident assertions’ (1 Tim. 1:6-7). In principle, desire to cross a culture and proclaim the gospel for the goal of making disciples does not equal competence to do so. Desire indeed inspires discipline to attain the necessary competence, but they are not equal. If your loved one had a brain tumor, though you had a desire to remove it, you would surely seek out a qualified neurosurgeon. Moreover, even if you were a credentialed massage therapist, you would never pretend that a scalp massage would fix the tumor. If this is the common logic we use in every other sphere of our temporal existence in this world, why do we settle for less when it comes to matters of eternal damnation and eternal life? To do so borders on cruel, unloving, and ministerial malpractice.
 Kevin DeYoung and Greg Gilbert, What is the Mission of the Church? (Wheaton: Crossway, 2011), 21.