it comes from three verses,
Jhn 5:22
For the Father judgeth no man, but hath committed all judgment unto the Son:
Jhn 8:15
Ye judge after the flesh; I judge no man.
Jhn 3:18
He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
God gives judgement to the Son, the Son says I do not judge after the flesh , I judge no man.
Yet we are condemned. If Adam was a man and condemned both him could not have been condemned AS A MAN, according to Jesus.
so He had to condemned BEFORE. Remember we are body and soul. The soul sins the body does not, according to Jesus.
So he had to be condemned as a soul, before he had a body