1 John 3:20

“For if our heart condemn us, &c.] Of want of love to the brethren, and of hypocrisy in it, as well as of any other sin; for the conscience, which is meant by the heart here, is accuser, witness and judge; it accuses of the evil of sin, and is as good as a thousand witnesses; and upon its own testimony pronounces guilty, and condemns. God is greater than our heart: for he is the Maker of it, and he has the power over it, and the management of it; it is in his hands, and to be turned by him as he pleases; and he is the searcher and trier of it; and besides, is a swifter witness than conscience, and a superior Judge unto it. And knoweth all things; that are in the heart; the principles of…”

“LUTHER and BENGEL take this verse as consoling the believer whom his heart condemns; and who, therefore, like Peter, appeals from conscience to Him who is greater than conscience. "Lord, Thou knowest all things: thou knowest that I love Thee." Peter's conscience, though condemning him of his sin in denying the Lord, assured him of his love; but fearing the possibility, owing to his past fall, of deceiving himself, he appeals to the all-knowing God: so Paul, Co1 4:3-4. So if we be believers, even if our heart condemns us of sin in general, yet having the one sign of sonship, love, we may still assure our hearts (some oldest manuscripts read heart, Jo1 3:19, as well as Jo1 3:20), as knowing…”

“For if our heart condemn us - We cannot hope for peace from any expectation that our own hearts will never accuse us, or that we ourselves can approve of all that we have done. The reference here is not so much to our past lives, as to our present conduct and deportment. The object is to induce Christians so to live that their hearts will not condemn them for any secret sins, while the outward deportment may be unsullied. The general sentiment is, that if they should so live that their own hearts would condemn them for present insincerity and hypocrisy, they could have no hope of peace, for God knows all that is in the heart. In view of the past - when the heart accuses us of what we have…”

“For if we have not this testimony, if in anything our heart, our own conscience, condemn us, much more does God, who is greater than our heart - An infinitely holier and a more impartial Judge. And knoweth all things - So that there is no hope of hiding it from him. 1 John 3:21”

“if: Job 27:6; Joh 8:9; Act 5:33; Rom 2:14, Rom 2:15; Co1 4:4, Co1 14:24, Co1 14:25; Tit 3:11 God: Jo1 4:4; Job 33:12; Joh 10:29, Joh 10:30; Heb 6:13 and: Psa 44:20, Psa 44:21, Psa 90:8, Psa 139:1-4; Jer 17:10, Jer 23:24; Joh 2:24, Joh 2:25, Joh 21:17; Heb 4:13; Rev 2:23 1 John 3:21”