Paul writes Christ is the propitiation through faith in His blood.
Romans 3:25 (KJV) Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
How can we reconcile Christ being the propitiation through faith in His blood with what John writes in 1Jo 2:2?
1 John 2:2 (KJV) And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.
After saying Christ is the propitiation for the whole world, why does John write that we should not love the world, neither the things in the world. And if a man loves the world, the love of the Father is not in him. That surely makes a distinction between those of faith in Christ, and being of the world, which is lust of the flesh, eyes and the pride of life that is not of the Father, but of the world. After saying Christ is the propitiation for the whole world, John writes "the world passes away".
1 John 2:15-17 (KJV) Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever.
Since the world shall pass away, how is Christ the propitiation for our sins, but also for the whole world? Though world can sometimes be defined as all of creation, including every human being, it cannot mean every human in this passage. If it did we have contradiction between the writing of Paul and that of John. We reconcile the two when we understand Christ as the propitiation for whosoever is of faith in His blood, and Christ is also the propitiation of the whole of creation (world) through His sacrificial blood shed on the cross. By His sacrifice and resurrection the whole world will be redeemed from the consequence that is death for everything living. Because all of creation, every living creature was subjected to death through man's sin. But since Christ is the propitiation (atonement; expiator) for ALL sin, so not only will all who are of faith in His blood be saved through Him, but creation also shall be saved (redeemed; made new again) through His atoning blood.
Romans 8:19-22 (KJV) For the earnest expectation of the creature waiteth for the manifestation of the sons of God. For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope, Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God. For we know that the whole creation groaneth and travaileth in pain together until now.
Revelation 21:1-5 (KJV) And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea. And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband. And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God. And God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away. And he that sat upon the throne said, Behold, I make all things new. And he said unto me, Write: for these words are true and faithful.
It is in this manner that Christ is the propitiation not only for our sins, but for the whole world!