The answer to the above question must be carefully qualified, in my humble opinion.
Both pursuits, offered out of a redeemed heart, are honoring to God. God has given His creation and His people the opportunity to labor for His glory (1 Co. 10:31). As with all things that we do, we have the opportunity to present our works and deeds to God as gifts. How do we do so? By performing them out of a heart of love. Though it is easy to get a bit over-heated about the nature of work–some theologians have oversold its value, as I see it–and see every task as ushering in the kingdom, it is clear from the Bible that work possesses inherent dignity when done to maximize God’s glory. Though the actual tasks we perform may not in themselves advance the kingdom (the kingdom is advanced primarily by proclamation and inherently spiritual activity, I would contend), yet our attitudes, our dispositions, and our constant devotion to God can well bless the Lord.
We see, then, that while making a shoe may not inherently advance the kingdom (the shoe possesses no spiritual value, after all), the attitude of the shoemaker (his worshipful heart expressing itself even as he sows the shoe together) and the good he accomplishes with the shoe (passing it on to a needy child in the name of Christ, for example) may well contribute to the forward movement of God’s kingdom. Not everything we do contributes to this forward progress, I would argue, but this is not to say that we cannot bring God glory in our daily goings-on and, perhaps often by means of our heart and our spiritually minded acts, claim some kingdom ground. We see, then, that the matter of work–indeed, all of our daily acts–becomes a matter of theological consideration, and requires us to carefully define the kingdom on biblical grounds.
With all of this said, the preaching of the gospel is the fundamental means of kingdom advancement. See Matthew’s first notation of kingdom-oriented preaching in 3:2–it is explicitly connected with the preaching of the gospel. Therefore, we should seek to preach the gospel to advance the kingdom, understanding that this is the primary–though not the only–means of pushing it forward. This means for those of us who work that we should indeed seek to preach the gospel in our workplaces. We should do so, however, shrewdly (Mt. 10:16). I don’t think it wise for a Christian to consider their primary on-the-job responsibility to be evangelism. That’s not honest. Your employer has hired you to be an accountant; be an accountant. Account. (Sorry, that’s a bad joke.)
However, be a shrewdly Christian accountant. Season your conversation with the gospel. Look for opportunities to talk about your church, your faith, your conversion. Ask co-workers if they would like to hang out, and then engage them in honest, normal, but spiritually oriented conversation. Read the Bible in your lunch hour, and keep it on your desk. Let people see that the Bible is an organic part of your life. But do all this while being an excellent accountant (or forester or truck-driver or librarian or politician or athlete or stay-at-home mom). Know accountant laws. Put in a hard, full work day. Be one of the best employees in your office. Be nice, polite, helpful, and kind. Do your work with excellence. In summary, be a worker whose Christianity is apparent, whose goodness is evident, and whose work is excellent. Honor your Lord, but do so while honoring your boss.
Many Christians, of course, work in environments hostile or at least unfriendly to Christianity. In this case, simply turn up the “shrewdness” factor. People are still desperately lost; they are still looking for light, to some extent; they will still be unable to avoid noticing an attractive Christian witness when it presents itself. Over time, they’ll ask questions and want to know what makes you tick, a situation helped, of course, by a Christian directing conversation well and living a life that looks and smells differently from others. Above all, Christians in these situations must look to share the gospel just as much as other Christians, though as noted they will need to do so with greater shrewdness than others. On the question of what to do when sharing faith involves the loss of a job, there is no black-and-white answer that I know of. One will have to balance faithful boldness with careful wisdom. One will have to do so, though, with Christ’s warning about being an unfaithful or fearful witness in mind. No reward is promised to the timid; much reward is promised to the courageous (see the beatitudes of Matthew 5).
In summary, the Christian must thus see himself as part of a cosmic movement of God’s Spirit that is orchestrated by the Father’s will and proceeds forth from the Son’s redemptive work. The Christian who goes off to work each morning should not simply think that he is putting in time and punching a clock; neither should he think that he is in some vague sense honoring God by working. No, he should realize that he is part of a kingdom movement, and he is able throughout the day to advance that kingdom by a godly attitude and disposition and by acts and deeds of gospel-oriented grace, justice, beauty, and goodness. We might restrain ourselves from saying that every task he performs directly contributes to this kingdom progress, but in doing so we would not make the mistake of thinking that only preachers accomplish spiritually meaningful things. No, all of us have the opportunity to participate by disposition and deed and word in this cosmic movement.
This perspective threatens to transform our daily rites, doesn’t it? However you’ve considered work, you need not see it in stark terms, either as an evangelistic endeavor alone or a clock-punching exercise. No, work is a beautiful blend of these things, an opportunity to, as I said earlier, send God little gifts of glory by the things we do and the words we say. As you head into the forest, or wheel into your desk, or walk customers around the car showroom, you are not cut off from the kingdom. You are right in the center of it. As you live with integrity, and model Christ’s grace and kindness, and speak gospel-saturated words, yes, you are right in the center of it. You may not know it, and no one may see it, but heaven is smiling on you in these times. And somehow, in ways imperceptible to human eyes and ears, a reign is being extended, a light is being lifted, and the earth and hills and stars are being readied to celebrate and surrender to the coming King.