And he is the atoning sacrifice{"atoning sacrifice" is from the Greek "hilasmos," an appeasing, propitiating, or the means of appeasement or propitiation-- the sacrifice that turns away God's wrath because of our sin.} for our sins, and not for ours only, but also for the whole world.
Those who know God will obey his Word. These are the true Christians. Their obedience results in assurance of salvation, greater love for God, and lives that become increasingly like the life of Christ (3-6).