World Wide Study Bible
a Bible passage
19. hereby—Greek, "herein"; in our loving in deed and in truth (1Jo 3:18).
we know—The oldest manuscripts have "we shall know," namely, if we fulfil the command (1Jo 3:18).
of the truth—that we are real disciples of, and belonging to, the truth, as it is in Jesus: begotten of God with the word of truth. Having herein the truth radically, we shall be sure not to love merely in word and tongue. (1Jo 3:18).
assure—literally, "persuade," namely, so as to cease to condemn us; satisfy the questionings and doubts of our consciences as to whether we be accepted before God or not (compare Mt 28:14; Ac 12:20, "having made Blastus their friend," literally, "persuaded"). The "heart," as the seat of the feelings, is our inward judge; the conscience, as the witness, acts either as our justifying advocate, or our condemning accuser, before God even now. Joh 8:9, has "conscience," but the passage is omitted in most old manuscripts. John nowhere else uses the term "conscience." Peter and Paul alone use it.
before him—as in the sight of Him, the omniscient Searcher of hearts. Assurance is designed to be the ordinary experience and privilege of the believer.