10 For this reason they also will henceforth keep silence, who once said that He who proceeded from Mary is not very Christ, or Lord, or God. For if He were not God in the Body, how came He, upon proceeding from Mary, straightway to be called 'Emmanuel, which is being interpreted God with us?' Why again, if the Word was not in the flesh, did Paul write to the Romans 'of whom is Christ after the flesh, Who is above all God blessed for ever. Amen?' Let them therefore confess, even they who previously denied that the Crucified was God, that they have erred; for the divine Scriptures bid them, and especially Thomas, who, after seeing upon Him the print of the nails, cried out 'My Lord and my God!'
For the Son, being God, and Lord of glory, was in the Body which was ingloriously nailed and dishonoured; but the Body, while it suffered, being pierced on the tree, and water and blood flowed from its side, yet because it was a temple of the Word was filled full of the Godhead. For this reason it was that the sun, seeing its creator suffering in His outraged body, withdrew its rays and darkened the earth. But the body itself being of mortal nature, beyond its own nature rose again by reason of the Word which was in it; and it has ceased from natural corruption, and, having put on the Word which is above man, has become incorruptible.
Source: Letters (New Advent)