>It is not because it is caffeine, it is because it i a simulate. The same goes with many soda drinks (despite the have ownership the Coke-cola company I have heard.)
This popular rumor is not true, according to the rumor experts:
http://www.snopes.com/cokelore/mormon.asp
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)