Think of it this way.
Why does Pate HAVE to have Christ walking sinlessly on his behalf, rather than only dying for Pate's sin?
Because Pate believes the work of a sinless walk is required for salvation, even though Paul never says it is.
He believes he cannot be saved unless he has BOTH Christ's sinless walk AND His death for sin credited to Pate's account. He insists upon it.
That means Pate believes the Cross isn't adequate to cover anyone's sin.
Paul said it is.
That means Pate is lost.
Jesus vicariously lived for us, died for us, ascended into heaven for us, is at the right hand of God for us and is coming again for us. If you don't believe that then you should not profess to be a Christian, simply because you are without a savior.
All that Jesus was and all that Jesus did, was for our salvation and our justification. When God accepted Jesus back into heaven we were accepted in him. No one will enter heaven that has not been justified by the doing and the dying of Jesus.