But if any man loves God Here we have the conclusion, in which he shows what is especially commendable in Christians, and even renders knowledge, and all other endowments worthy of commendation, if we love God; for if it is so, we will also love our neighbors in him. By this means all our actions will be properly regulated, and consequently approved by God. He shows, therefore, from consequences, that no learning is commendable that is not dipped in the love of God; because that alone secures, that whatever endowments we have are approved by him, as it is said in the second Epistle -- If any man be in Christ he is a new creature. (2-Corinthians 5:17.) By this he intimates, that without the Spirit of regeneration, all things else, whatever they may have of show, are of no value. To be known by God means to be held in any estimation, or to be reckoned among his sons. Thus he erases all proud persons from the book of life, (Philippians 4:3,) and from the roll of the pious.

But if any man love God - If any man is truly attached to God; if he seeks to serve him, and to promote his glory. The sense seems to be this. "There is no true and real knowledge which is not connected with love to God. This will prompt a man also to love his brethren, and will lead him to promote their happiness. A man's course, therefore, is not to be regulated by mere knowledge, but the grand principle is love to God and love to man. Love edifies; love promotes happiness; love will prompt to what is right; and love will secure the approbation of God." Thus, explained. this difficult verse accords with the whole scope of the parenthesis, which is to show that a man should not be guided in his contact with others by mere knowledge, however great that may be; but that a safer and better principle was "love, charity" (ἀγάπη agapē), whether exercised toward God or man. Under the guidance of this, man would be in little danger of error, Under the direction of mere knowledge he would never be sure of a safe guide; see 1-Corinthians 13:1-13.
The same is known of him - The words "is known" (ἔγνωσται egnōstai) I suppose to be taken here in the sense of "is approved by God; is loved by him; meets with his favor, etc." In this sense the word "known" is often used in the Scriptures. See the note at Matthew 7:23. The sense is, "If any man acts under the influence of sacred charity, or love to God, and consequent love to man, he will meet with the approbation of God. He will seek his glory, and the good of his brethren; he will be likely to do right; and God will approve of his intentions and desires, and will regard him as his child. Little distinguished, therefore, as he may be for human knowledge, for that science which puffs up with vain self-confidence, yet he will have a more truly elevated rank, and will meet with the approbation and praise of God. This is of more value than mere knowledge, and this love is a far safer guide than any mere intellectual attainments." So the world would have found it to be if they had acted on it; and so Christians would always find it.

But if any man love God - In that way which the commandment requires, which will necessarily beget love to his neighbor, the same is known of him - is approved of God, and acknowledged as his genuine follower.

But if any man love God,.... As they do, and show it, who love their brethren, and are careful not to grieve them; and make use of their superior knowledge, not for their destruction, but edification:
the same is known of him; is taught by him, made to know more by him; such an one increases in spiritual knowledge, or he is highly approved of, esteemed, and beloved by God: he takes a special and particular notice of him, manifests his love to him, and will own and acknowledge him another day, when proud, haughty, overbearing, and hard hearted professors, will be rejected by him.

love God--the source of love to our neighbor (1-John 4:11-12, 1-John 4:20; 1-John 5:2).
the same--literally, "this man"; he who loves, not he who "thinks that he knows," not having "charity" or love (1-Corinthians 8:1-2).
is known of him--is known with the knowledge of approval and is acknowledged by God as His (Psalm 1:6; Galatians 4:9; 2-Timothy 2:19). Contrast, "I never knew you" (Matthew 7:23). To love God is to know God; and he who thus knows God has been first known by God (compare 1-Corinthians 13:12; 1-Peter 1:2).

He is known - That is, approved, by him. Psalm 1:6.