Christ is the Word of God, but the Word became flesh. Christ therefore suffered and died, but in the flesh. In this respect, the ram is the type, just as John said: Behold the lamb of God, behold him who takes away the sins of the world. The Word, however, remained incorruptible. This is Christ according to the spirit, and Isaac is the type. Therefore, Christ himself is both victim and priest according to the spirit. For he offers the victim to the Father according to the flesh, and he is himself offered on the altar of the cross.
From a homily on Genesis by Origen, priest