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.

 His object in writing is that they may not sin. There is a two-fold connection of thought here--with what has gone before and with what comes afterwards. There is a two-fold danger that they may indeed think lightly of sin. 