Whistle Stop...I don't think you have to be a cynic to recognize the sense of your "logo" argument. Christianity is and was an evangelical belief, spreading from the Middle East throughout the world. The cross as a symbol would have been an extraordinary conversation starting point. The incidents surrounding Christ's crucifixion and resurrection, quite apart from the inherent moral code and rituals within Christianity, made for great storytelling. Martyrdom is a fascinating topic, especially for a cause, and especially when that cause is the promise of Heaven for all mankind.

As with any powerful symbol, the cross is more than a nifty design icon and door-opener. It is important for all the reasons listed in my previous post, and for historical reasons, both as an object of worship and as a target for iconoclasts.