Why can salvation be taught as based on the finished work of the cross plus nothing?
Salvation can be taught as the finished work of the cross plus nothing because the law said one hanged on a tree is accursed of God, and that pictured Christ, who was made sin for us. His finished work fully answered that curse, so nothing else needs adding.
Les explains that the command not to leave a hanged man on the tree overnight, and the statement that he is accursed of God, was a preview of what Christ accomplished in our behalf. He then points to II Corinthians 5:21, where God hath made him to be sin for us. The rebel's stoning and public hanging pictured the curse and spectacle, but it pointed to Christ. Therefore, because Christ was made sin and dealt with that curse, the teacher can stand and teach a total salvation based on the finished work of the cross, plus nothing.
And if a man have committed a sin worthy of death, and he be to be put to death, and thou hang him on a tree:
See the restFor he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.