1 John 2:2

And he--Greek, "And Himself." He is our all-prevailing Advocate, because He is Himself "the propitiation"; abstract, as in Co1 1:30 : He is to us all that is needed for propitiation "in behalf of our sins"; the propitiatory sacrifice, provided by the Father's love, removing the estrangement, and appeasing the righteous wrath, on God's part, against the sinner. "There is no incongruity that a father should be offended with that son whom he loveth, and at that time offended with him when he loveth him" [BISHOP PEARSON]. The only other place in the New Testament where Greek "propitiation" occurs, is Jo1 4:10; it answers in the Septuagint to Hebrew, "caphar," to effect an atonement or reconciliation with God; and in Eze 44:29, to the sin offering. In Rom 3:25, Greek, it is "propitiatory," that is, the mercy seat, or lid of the ark whereon God, represented by the Shekinah glory above it, met His people, represented by the high priest who sprinkled the blood of the sacrifice on it. and--Greek, "yet." ours--believers: not Jews, in contrast to Gentiles; for he is not writing to Jews (Jo1 5:21). also for the sins of the whole world--Christ's "advocacy" is limited to believers (Jo1 2:1; Jo1 1:7): His propitiation extends as widely as sin extends: see on Pe2 2:1, "denying the Lord that bought them." "The whole world" cannot be restricted to the believing portion of the world (compare Jo1 4:14; and "the whole world," Jo1 5:19).

— Jamieson-Fausset-Brown Commentary (public domain)