John 8:31

“Then said Jesus to those Jews that believed on him, etc.] For he knew instantly who they were, and when they believed on him; and therefore he immediately turned himself to them, and thus addressed them; if ye continue in my word; meaning the Gospel, called his, because he was both the author, and preacher, and sum, and substance of it: and to continue in it, is having cordially received it, to abide by it, and hold it fast, and not to be moved from it, by the temptations of Satan; the cunning of those that lie in wait to deceive; nor by the revilings and persecutions, the frowns and flatteries of men: and when men continue thus steadfast in it, and faithful to it, it is an evidence that it…”

“Then said Jesus to those Jews who believed, If ye continue in my word, then are ye my disciples indeed, &c.--The impression produced by the last words of our Lord may have become visible by some decisive movement, and here He takes advantage of it to press on them "continuance" in the faith, since then only were they His real disciples (compare Joh 15:3-8), and then should they experimentally "know the truth," and "by the truth be made (spiritually) free."”

“If ye continue in my word - If you continue to obey my commandments and to receive my doctrines. Then are ye ... - This is the true test of Christian character. John 14:21; “he that hath my commandments and keepeth them, he it is that loveth me.” See John 2:4; Joh 3:24; 2 John 1:6. In this place Jesus cautions them against too much confidence from their present feelings. They were just converted - converted by a single sermon. They had had no time to test their faith. Jesus assures them that if their faith should abide the test, if it should produce obedience to his commandments and a truly life, it would be proof that their faith was genuine, for the tree is known by its fruit. So we may…”

“8:31-32 Discipleship is more than knowing who Jesus is. It is also about obeying his teachings (3:36; 14:15, 21, 23; 15:10). • Because Jesus is the truth (14:6), knowing him brings discernment of what is true and what is false. • set you free: The truth brings freedom from darkness, falsehood, and sin.”

“If: Joh 6:66-71, Joh 15:4-9; Sa1 12:14; Mat 24:13; Act 13:43, Act 14:22, Act 26:22; Rom 2:7; Rom 11:22; Col 1:23; Ti1 2:15, Ti1 4:16; Ti2 3:14; Heb 3:14, Heb 8:9, Heb 10:38, Heb 10:39; Jam 1:25; Jo1 2:19, Jo1 2:24 my disciples: Joh 8:36, Joh 1:47, Joh 6:55, Joh 15:8; Ti1 5:3-5 John 8:32”