His body was in a tomb.
His soul was in Hell, the center of the earth, which would, until the resurrection, contain two compartments : Paradise and "Torments" (a place of burning punishment).
Christ descended into Hell, left our sins there after suffering ; then went through Paradise with the Keys of Hell and of Death, opening the door of Paradise personally and leading "captivity captive," the OT Saints whose souls were there until the Redemption, the "cutting off of Messiah" (Daniel ch. 9) and the Resurrection of Christ, which made the Third Heaven accessible.
This is what "the gates of Hell" not prevailing against the church of Matthew 16 is dealing with. The "Assembly" of the saints could not forever be kept confined in "Hell" (the lower parts of the earth, still containing Abraham's Bosome until then) -- the gates of Hell could NOT prevail against them when Christ with the keys of Hell and death opened the doors to let them out and lead them into the Third Heaven, God's immediate presence.
And more, and more . . .
John Leland, you said it very well in your post here...I did not see this before posting my comments (No. 146) in this thread, but I do not disagree with you. You are correct. The Word is supportive of your comments. Thank you.