John Calvin on John 3:21

21. But he who doeth truth This appears to be an improper and absurd statement, unless you choose to admit that some are upright and true, before they have been renewed by the Spirit of God, which does not at all agree with the uniform doctrine of Scripture; for we know that faith is the root from which the fruits of good works spring. To solve this difficulty, Augustine says, that to do truth means “to acknowledge that we are miserable and destitute of all power of doing good;” and, certainly, it is a true preparation for faith, when a conviction of our poverty compels us to flee to the grace of God. But all this is widely removed from Christ’s meaning, for he intended simply to say that those who act sincerely desire nothing more earnestly than light, that their works may be tried; because, when such a trial has been made, it becomes more evident that, in the sight of God, they speak the truth and are free from all deceit. Now it would be inconclusive reasoning, were we to infer from this, that men have a good conscience before they have faith; for Christ does not say that the elect believe, so as to deserve the praise of good works, but only what unbelievers would do, if they had not a bad conscience.

Christ employed the word truth, because, when we are deceived by the outward lustre of works, we do not consider what is concealed within. Accordingly, he says, that men who are upright and free from hypocrisy willingly go into the presence of God, who alone is the competent Judge of our works. For those works are said to be done in God or according to God, which are approved by Him, and which are good according to His rule. Hence let us learn that we must not judge of works in any other way than by bringing them to the light of the Gospel, because our reason is wholly blind.

John 3:22-28

22. After these things came Jesus, and his disciples, into the land of Judea, and there he remained with them and baptized. 23. And John also was baptizing in Enon, near Salim; because there were many waters there. They came therefore and were baptized. 24. For John was not yet cast into prison. 25. A question then arose between the disciples of John and the Jews about purifying. 26. And they came to John, and said to him, Rabbi, he who was with thee beyond Jordan, to whom thou gavest testimony, lo, he baptizeth, and all men come to him. 27. John answered and said, A man cannot receive any thing, unless it be given to him from heaven. 28. Yourselves are witnesses to me, that I said, I am not Christ, but was sent before him.