Sometimes the slogan “All truth is God’s truth” is used to justify dealing in any sphere of knowledge as an act of worship or stewardship. The impression is given that just knowing God’s truth and recognizing it as such is a good thing, even a worthy end. But the problem with this is that the devil does it also.
“If anyone imagines that he knows something, he does not yet know as he ought to know. But if anyone loves God, he is known by God.” (1Corinthians 8:2-3). Which I take to mean that until we know in such a way that we love God more because of it, we do not yet know as we ought to know.
Alongside “All truth is God’s truth,” we need to say, “All truth exists to display more of God and awaken more love for God.” This means that knowing truth and knowing it as God’s truth is not a virtue until it awakens desire and delight in us for the God of truth. And that desire and delight are not complete=2 0until they give rise to words or actions that display the worth of God. That is, we exist to glorify God (1 Corinthians 10:31), and merely knowing a truth to be God’s truth does not glorify him any more than the devil does.
All truth exists to make God known and loved and shown. If it does not have those three effects it is not known rightly and should not be celebrated as a virtue.
I give thanks that unbelievers see God’s truths in the natural world in a limited way. They know many scientific and cultural facts. But they do not feel desire for God or delight in God because of them. So these facts are misused. This is not a virtue.
I also give thanks that that believers may learn many of God’s truths from unbelievers and see them rightly and thus desire God more and delight in God more because of those truths, so that unbelievers become, unwittingly, the means of our worship.
Thus an unbeliever’s knowing God’s truth is not ultimately a virtue—that is, not a knowing that accords with God’s purpose for knowing—nevertheless that knowing may be a useful knowing for the sake of what God makes of it for his self-revealing and self-exalting purposes in the world, contrary to all the expectations of the unbeliever whose knowing God uses.
It is fitting, therefore, for love's sake—for God's sake—that believers learn what we can from unbelievers who see many things that we may miss, but do not see the one thing needful.
- John Piper