The Atonement is one of those funny things in Christianity. It is the central tenet, the main raison d’etre of the whole shebang. Jesus existed as God incarnate in order to be sacrificed and die in order to pay for our sins, past, present and future.
Only it makes absolutely no sense.
In very simplistic terms, I see it like this:
Firstly, let us assume the classical theistic notion of God who has perfect foreknowledge. He has knowledge of all future events and counterfactuals (if this, then that). So now we have this situation where God is creating and has full knowledge at exactly what he is creating. This actually means that God has at least some moral culpability for sins committed by humanity.
Analogy: I create a sentient lifeform in the lab. I design this from scratch. I could have done it otherwise but I choose to do it like this.
I know this lifeform will escape from my lab and go and murder people in town. I know this utterly. They do this using the mechanisms which I have designed into them. Imagine one of these people they kill is your daughter. And yet, even knowing this destruction they will cause, I decide to create them anyway.
The police knock at my door. They say it is my fault.
But, using the Christian’s logic, I deny this, arguing they used their own mechanisms to murder.
But the police say that I designed those mechanisms, knew what they would do, created them anyway, and then let them run amok.
The police laugh off my defence. They lock me up.
That’s the end of the mad scientist who created evil beings.
Another analogy would be this. I am CEO of a car company. I design a car which I know is faulty. I know exactly when it will be faulty and crash to cause injury and death. I know this and create it anyway. The car fulfils its destiny and causes death. I, as CEO who also designed and manufactured the car, am rightfully held responsible.
So we have this scenario where God creates humanity knowingly to sin. He then sacrifices himself to himself (whilst also praying to himself) to sit on his own right hand in heaven for eternity.
Firstly, this is no big sacrifice. Indeed, this seems in reality a very small sacrifice. I can imagine far more noble and greater sacrifices from mere humans than this. Secondly the need for payment is pointless. Why God would need in any way to balance the books is beyond me; and why this sacrifice would balance the books at all is beyond me.
There is nothing about the Atonement that makes any sense to me.