"But I came upon a question immediately. What does this statement mean? " "The soul when it was deified descended into Hades" Is there a moment that Jesus was not deity???"
The translation isn't the best, but likely the best that can be done in English. Two things are being said. First, that it was the Divine Soul of Christ which descended to the place of the Dead, having been released from the Body and second, that this is the one instance in history where we can say that God died (the converse, of course, is that we find in the person of Christ the one instance where we can say that man is eternal).
I forgot to add that I also earlier posted a link to +Athanasius on the Incarnation which also speaks to the meaning of the Sacrifice on the Cross within the context of God's plan advancing through the Incarnation.
It may be in this Chapter: The Death of Christ
"Here, then, is the second reason why the Word dwelt among us, namely that having proved His Godhead by His works, He might offer the sacrifice on behalf of all, surrendering His own temple to death in place of all, to settle man's account with death and free him from the primal transgression. In the same act also He showed Himself mightier than death, displaying His own body incorruptible as the first-fruits of the resurrection…"