I found this little nugget in C.S. Lewis’s work, Christian Apologetic. He states:
“The difficulty we are up against is this. We can make people (often) attend to the Christian point of view for half an hour or so but the moment they have gone away from our lecture or laid down our article, they are plunged back into a world where the opposite position is taken for granted. As long as that situation exists, widespread success is simply impossible. We must attack the enemy’s lines of communication. What we want is not more little books about Christianity, but more little books by Christians on other subjects–with their Christianity latent… You can see this most easily if you look at it the other way round. Our faith is not very likely to be shaken by any book on Hinduism. But if wherever we read an elementary book on Geology, botany, Politics, or Astronomy, we found that its implications were Hindu, that would shake us.”
Not everyone is called to write Theology. Not everyone is called to preach, or sing, or teach. There are more to the Lord’s service that does not involve these. Say, for instance, my bi-vocation–nursing. Nursing from a Christian impulse of compassion, skill, sacredness of life, theistic worldview , etc., can do more in the way of displaying God’s glory than if that said nurse would endeavor to write a systematic theology volume. (However, if the nurse is good at both then the Lord as obviously deposited more talents into their charge: it would be irresponsible not to use both.) But if the nurse, out of zeal, spent enormous time and energy writing the volume that is sub-par at best, then one wonders if their time may have been better spent providing God glorifying care to the sick.
So my point is God has called us to glorify Him through our various vocations. The very presence, sense of purpose/mission, that will lace our service will be sufficient to point people beyond ourselves and unto God. I argue that if our services end upon ourselves, that is to gain a paycheck for spending, then it is vanity. But if our services ended upon bringing glory to God, then this is the essence of evangelism. I would go as far as to say even our sufferings and trials should not end or be counted as useless, but should be means by which God’s glory can be known.
So, plumb, nurse, wield, teach, preach, sing, write all to the glory of God. Suffer to the glory of God. Live in health to the glory of God. Be poor to the glory of God. Knowing that in our weakness, poverty, sickness, health, we are all overly satisfied with and displaying the glory of God. This is our highest purpose.