A failure to be faithful to the fundamental, sound doctrines of the faith (a proper view of the person and work of Christ, love, obedience) marks a person as having never been born again (1 John 2:23; 3:6-10; 4:20,21; 5:1-3). The word “abide” has the idea of constant adherence and warns that these fundamentals are not open to change or subject to the latest trends or philosophical fads.
Commentary from the MacArthur study Bible, notes for 2 John 9.
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