think a lot of this conflict just a basic misreading of "atonement" and the day of atonement. if you don't understand the leviticus ritual, you can't understand the reference St Paul makes to it when talking about the cross.
"atonement" doesn't and can't mean "forgiveness of sins". the priest "makes atonement" for the altar, the mercy seat, and they are inanimate objects. we have to remember "atonement" was a made-up word for english used to translate the hebrew word "kephar" which is related to covering (noah covers the ark with pitch - same word). the chapter after the day of atonement ritual explains - blood is given on the altar to "cover" for our souls, and the blood makes a covering by life.
leviticus is clear that sin leaves a stain or a residue, sin is the stuff of death. when the people commit individual sins, they leave that stain of sin on the camp. the stuff of life, the blood, is used to cover and obviate or cancel out that stuff of death. God cannot be in the presence of sin because His holiness will consume it (meaning the people and the camp).
the day of atonement has several parts:
- two goats and a bull are used. lots are cast to pick between two goats - one for God, one for azazel (the devil)
- the high priest sacrifices a bull as a sin offering to cover the sins of himself and his family. he fills the holy place with a cloud of incense (to prevent him from seeing God and dying) and takes the blood of the bull and sprinkles it on the mercy seat.
- then he kills the goat to cover the sins of the people, and uses that blood to sprinkle inside the veil again.
- those two sprinklings cover for the sins of the people and their uncleanness.
- he does the same for the tent of meeting, and then for the altar
- next he takes the other goat (for azazel) and confesses over it the iniquities, transgressions, and sins of the people. this goat is not sacrificed. it is unclean, it cannot be sacrificed to God. it is led out to the wilderness, taking the sins of the people with it - back to the devil, where they came from.
- then he washes himself, takes the fat from the bull and the goat and burn them on the altar. the rest of the offerings are taken outside of the camp and burned.
the atonement / covering ritual takes "life stuff" and uses it to cover up and clean "death stuff". the sins themselves are taken away and removed. their residual taint / filth are cleaned by blood. this must be repeated year after year, because the high priest still sins, and the people still sin. if it is not, God cannot dwell there in the midst of sin.
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so how then do we understand the cross as atonement? St John mixes his metaphors when he says "behold the lamb of God who takes away the sin of the world." Sin is singular, not plural. Not the 'sins' but sin.
the short answer is Christ Jesus is both goats. He is the goat which is sacrificed, pure, and His blood makes a covering for the residual taint of sin - over the whole world. This is why St Paul says "He became [a sin offering] for us." That is what the goat for Yahweh is - a sin offering. That's why St Peter says "he bore our sins in His body on the tree."
But He is also the goat which takes on the sins of the people, but rather than becoming unclean, He makes them clean. We see this multiple times in His ministry when he encounters uncleanness and cleanses it rather than becoming unclean Himself. Darkness meets Light, and the Light overcomes the darkness. Death encounters Life, and Life consumes it.
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now maybe we can go back to the original question. how did Christ's atonement affect people? everyone, or some? the answer is clearly everyone - this is the only reason the people of the other nations could approach and worship God, or have His Spirit dwell within them. they were unclean, now they have been made clean: "do not call anything impure what God has made clean."
this allows the gentiles, the people of the other nations, to come close - as St Paul says, "But now in Christ Jesus you who once were far away have been brought near." How? "through the blood of Christ." That is, through the atonement. His covering sacrifice overlooked the previous sins, "through the shedding of His blood" to be received by faith, with no distinction between Jew or Gentile.
Why do we who are made unclean by sin have confidence to enter the Most Holy Place? because of this atonement - "by the blood of Jesus" who is the great high priest.
This atonement, covering, reconciled the world - not just Israel - to God (2 Cor 5:19) and so "He is the covering for our sins, and not only for ours, but for those of the whole world."
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does this mean all are saved? no - because being able to draw near, having your former sins overlooked, says nothing about whether you will wash yourself and be clean, turn from your evil ways, hate evil and do good, etc.
But the scriptures are clear - the atonement / covering was once for all. that is why all nations can draw near ot Christ Jesus and have the Holy Spirit dwell within them.
