I suppose that first-generation Christians must have started wearing crosses as symbols of hope, which the both the living and the risen Christ represented. The cross was the "electric chair" of Roman times...it was the form of death reserved for common criminals. When Christ died on the cross He was not glorifying criminals per se, (don't think He did not choose the manner of His death) believe He was making a statement about the plight of humankind and the symbol of hope He was. "Through Me you are sanctified, if you so choose." Thereafter, the cross itself became a holy symbol, no longer a thing of fear and dread. The cross must have represented our sinful human selves. (Taylor Caldwell explored this concept in her MUST READ novel of St Luke, "Dear and Glorious Physician." )The cross shape--not the sharp-planed cross, but the slightly rounded Egyptian ankh, was a symbol of divinity and healing, worn by Egyptian physicians. Also, the image of Mother and Child was "copied" from the Egyptian of Isis and infant Osiris...many people (including my dear departed mother) took this to mean that Chritianty was a fake since it utilized far older pagan symbols. I choose to say that rather it was Christ Himself Who did the intentional "copyright infringement"...by consciously choosing the great symbols of the pagan past to better communicate with those who would believe. If you can make sense of that. He knew His audience, so to speak.
I'm not surprised that no Christian would take part, though it is unfortunate. The issue of Christ's divinity is non-negotiable; imagine if Christians did a film about the Dome of the Rock and invited Moslems as well as Jewish and Christian scholars to debate whether or not Mohammed flew up to heaven on a winged horse from that spot. They'd go ballistic--since it's that premise which gives them rights to that prime piece of real estate. As well as challenging his divinity, so to speak! We Christians don't believe Mohammed became divine any more than they believe Jesus was. You may as well say to the Jews that the Western Wall isn't a remnant from Solomon's Temple, but from Herod's chintzy 3rd-generation knockoff, so they have no real claim to Jerusalem; same idea. I could go on and on.
Far better is to explore what specifuically made Jesus a Prophet in their eyes. I read the Koran a long tome ago and I can't recall the verses aobut Jesus. I have two Jordanian friends and I wanted to bring this up but thought it would hrt their feelings. What exactly were His teachings? If He wasn't divine and didn't a "ministry", what did He teach? Wonder if any parables or the Sermon on the Mount made it in there (minus the loaves and fishes.) Did He do any healing. Wish I could ask this.