Sacrificial love for fellow believers is a sure and certain sign that we possess saving faith and are children of God; this love is a love of action not just words, and produces in those who exercise it confidence about their right standing with the Father.
OUTLINE OF THE TEXT:
I. The Certainty (vv.14-15): Love for other believers demonstrates that we are genuinely converted and, as such, are children of God ("we know" v. 14)
b) Hating=murder ("We wish him to perish whom we hate"--John Calvin)
II. The Compassion (vv.16-18): Genuine Christian love is self-sacrificing and is demonstrated by deeds and not just words ("He laid down his life...we also ought to lay down our lives..." v. 16).
III. The Confidence (vv.19-24): The exercise of genuine Christian love produces confidence that we belong to God ("we have confidence before God" v.21).
a) Confidence in his presence (v.19).
b) Confidence in prayer (v.22).
c) Confidence by the Holy Spirit (v.24).