Why "walked away"? Doesn't Christianity celebrate the human sacrifice of Jesus? Seems quite similar to what the Native Americans did...
The death of Jesus was about the deepest expression of love that Jesus had for his creation. It was not about human sacrifice. It was like if a father was a judge and he took the place of his son who committed a crime. Jesus died so that anyone who would repent of their sins and put their trust in Him would be forgiven and granted the gift of everlasting life.