Expositor's Bible Commentary Commentary 1 John 4:13

"hereby we know that we abide in him and he in us, because he hath given us of his Spirit." — 1 John 4:13 (ASV)

Reciprocal abiding (2:24; 4:13, 15—God in us, we in God) is the final expression of fellowship with God. It is possible only through the gift of his Spirit, by whom the relationship with the Father and with the Son is sealed eternally (cf. Ephesians 1:13–14). Reciprocal abiding makes possible God’s love for us and our love for him. It is also the reason we can love one another.