Sacrifice without cost?

Chronicles21:24KJV" And king David said to Ornan, Nay; but I will verily buy it for the full price: for I will not take that which is thine for the LORD, nor offer burnt offerings without cost."

King David realized that a cost free sacrifice is in effect no sacrifice at all. Yet is this not the effect that Christendom's theology re: Christ being the God-man and unconditional immortality have on the supposed atonement. Christendom's reductive spiritualism has the effect of rendering the physical body (somos) worse than useless, a prison of rotting flesh that anchors our "real selves" to the ground during our probation on this earth. Surely being liberated from any prison is a blessing and not a sacrifice.

Matthew20:28KJV"Even as the Son of man came not to be ministered unto, but to minister, and to give his life(gk.psyche) a ransom for many." 

Obviously if Christ's real self(soul) was immortal or if he was god-man or both he could not give his soul as a ransom. The mere liberation of his true self from its prison of flesh would constitute no genuine sacrifice. For Christ atonement offering to be genuinely  substitutionary his death would have to be identical in nature to that of the first Adam.

1Corithians15:21KJV"For since by man came death, by man came also the resurrection of the dead. "

And as to nature of the first Adam's death, let's not speculate, but let JEHOVAH'S word be the authority.

Genesis3:19KJV"In the sweat of thy face shalt thou eat bread, till thou RETURN unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou RETURN."

Thus Adam was to RETURN to his pre-creation state. That is what death meant to Adam. For the second Adam to to serve as a genuine substitute to the first and thus effect an atonement his death MUST have the same significance.