If any of our own people also inquire, not from love of debate but from love of learning, why Jesus suffered death in none other way save on teh cross, let him also be told that no other way than this was good for us, and that it was well taht the Lord suffered this for our sakes.
For if he came himself to bear the curse laid upon us, how else could he have “become a curse,” unless he received the death set for a curse? And that is the cross. For this is exactly what is written: “Cursed is he that hangeth on a tree.”
Again, if the Lord’s death is the ransom of all, and by his death “the middle wall of partition” is broken down, and the calling of the nations is brought about, how would he have called us to him, had he not been crucified?
For it is only on the cross that a man dies with his hands spread out. Whence it is fitting for the Lord to bear this also and to spread out his hadns, that with the one he might draw the ancient people, and with the other those from the Gentiles, and unite both in himself.”
For this is what he himself has said, signifying by what manner of death he was ransom to all: “I, when I am lifted up,” he says, “shall draw all men unto me.”
And once more, if the devil, the enemy of our race, having fallen from heaven, wanders about our lower atmosphere, and there bearing rule over his fellow spirits, as his peers in disobedience, not only works illusions by their means in them that are deceived, but tries to hinder them that are going up…; while the Lord came to cast down the devil, and clear the air and prepare the way for us up into heaven, as said the apostle: “Through the veil, that is to say, his flesh” –and this must needs be by death–well, by what other kind of death could this have come to pass than by one which took place in the air, I mean the cross?
For only he that is perfected on the cross dies in the air. Whence it is fitting that the Lord suffered this death. For thus being lifted up he cleared the air of the malignity both of the devil and of demons of all kinds, as he says: “I beheld Satan as lightning fall from heaven”; and made a new opening of the way up into heaven, as he says once more: “Lift up your gates, O ye princes, and be ye lifted up, ye everlasting doors.”
For it was not the Word himself that needed an opening of the gates, being Lord of all; nor were any of his works closed to their maker; but we it was that needed it, whom he carried up by his own body. For as he offered it to death on behalf of all, so by it he once more made ready the way into the heavens.
From On the Incarnation.