And he is the b propitiation for our sins: and not for ours only, but also for [the sins of] the c whole world.
(b) Reconciliation and intercession go together, to give us to understand that he is both advocate and high priest.
(c) For men of all sorts, of all ages, and all places, so that this benefit being not to the Jews only, of whom he speaks as appears in (1 John 2:7) but also to other nations.
So if we take what John is saying in light of the physical context in which he is in, he is telling his audience of that day, that salvation is for more than the Jews. It's for people of all nations....all over the world. This interpretation is in keeping with the references mentioned above that indicate no one can come to Christ unless the Father draws him, or the place in John 12 and Romans 9 where it says God hardens and blinds some.
But the main point John is driving at in this book is that he wants us to walk in the light as He is in the light so that we will not sin. However, when we do sin, we have an advocate with the Father. Jesus Christ's sacrifice for our sin has satisfied the Father's justice and wrath against sin for those He has given to Him. What a comfort to know that!