When was the concept of divine sacrifice originated for removing human sins? Was this concept existed in the time of Adam (عَلَيْهِ السَّلاَمُ)?
Let’s go back in time to the first human being on the face of this Earth and his mate, his wife – Adam and Eve. When Allah created them and placed them in the garden, He did not leave them there without guidance. He gave them a way of life, a way of life which addressed their nature and the world in which they were placed. That way of life was, without any shadow of doubt, Islam. It was true Islam!
And the path to Islam was through guidance, divinely revealed guidance. The path was very short. Allah revealed to Adam exactly what was required of him. The essence of it was submission. Adam and his wife were given a garden of trees in which they could eat from any tree they wished, any tree except one. That one was the test of submission. They failed the test. They disobeyed Allah.
However, Allah in His grace and mercy, having taught them the true religion, taught them that salvation lies in repentance. Because it is the nature of human beings to sin, therefore knowing that that is the nature in which Allah has created human beings, a way out of that sin had also to be taught. So Allah taught Adam words of repentance – how to turn back to Allah sincerely and remove the sin of disobedience from themselves.
And that is why from the Islamic perspective there is no original sin that would then be handed down generations after generations, piling up, gathering momentum till it reached the time at the beginning of the years which are considered to be CE (Christina Era), from which point onwards when a divine sacrifice was necessary according to the teachings of Christianity. A divine sacrifice was necessary to remove sin from human beings. That is a fable. It is a story which was made up, which has no foundation in truth. Jesus never taught it. People made it up afterwards to justify their deification of Jesus.
Jesus followed the same religion – Islam – as the prophets who came before him. Salvation was by turning to God and asking Him for His forgiveness. That is how people gained salvation from sin. And that had been the tradition all the way till the time of Jesus. So that path represents a path of the true religion of God or the true path to Islam. Knowing human nature and addressing it.
Again going back to the time of Adam, the religion which was given to him, we as Muslims believe, was Islam. It could not possibly have been Christianity or Judaism or Buddhism or Zoroastrianism or any of the other religions that were based on the founders who were born many generations later. The religion which was required of him was one of submission and that is the definition of Islam. Islam means submission to the will of Allah. So that’s why we can confidently say that the religion of Adam and Eve was the religion of Islam.
The true path to understanding that religion was through revelation. And that path hasn’t changed. Time passed. People drifted away from that religion for one reason or another. Prophets were sent to call them back, instructing the people to do the same thing – to worship Allah alone and not to worship other Gods besides Him. This is stated in Qur'an, when Allah said,
“And We certainly sent into every nation a messenger, [saying], "Worship Allah and avoid Taghut…" 
That was the essential message. That is an essential part of true religion of God. That in Arabic is what we refer to as tawheed – worshipping Allah alone.
 [Qur’an 16:36]< Back to Questions