I saw a quilt made by Don Locke who is/was a dentist that was titled The Supper. Yes, it is a quilt of the Last Supper. He use 1/2 inch squares too and there were 51,816 of them but I don't think this was his first quilt. You can go here
http://thesupper.net/ to see and read about it. I saw it in person a number of years ago and could not believe it so I am sure I would feel the same about yours. Perhaps there is some information about how his was quilted on that site. (Linda Taylor of TX quilted it.) Perhaps you could even contact him via that site to ask about it. I know it was hung on some sort of frame when I saw it and it appeared stable but I cannot remember now how it was quilted. It's 183" X 67". Really awesome!!!