"And, while Christ was actually taking upon himself the sins of men, God condemned that sinful nature." Romans 8:3b
Did you know that, from the very beginning of the Church, all the way back to the Early Church days, up till now, there has never been one clear theology of the mechanics of the atonement? There are all kinds of opinions about how it all works - how our sin was covered by His blood, His death - but there has never been one overriding, agreed-upon "THIS IS EXACTLY HOW IT HAPPENED" sort of statement, even all the way back in the writings of the Early Church Fathers.
So I delight in the simplicity of Paul's statement - "Christ was actually taking upon himself the sins of men" - and its corollary - "God condemned that sinful nature." To put it in even simpler terms:
Our sin was put upon Jesus.
He died with it.
It died with Him.
You and I stand on the other side of history from the sinful nature; between us and it is Jesus, there, on the Cross.
I was reading this week (and perhaps you've already heard something like this before) where the writer very clearly made the following point: No matter how people explain their theology of the mechanics of the atonement, the important thing is that we all agree with the definition found within the spelling of that word in English:
What Jesus did on the Cross has forever set us free from sin and has given us opportunity to be "AT ONE" - in union - with God. The Cross re-bridges the divide started in Eden. For us, the Cross begins a new existence: a Union-Eden.