They require 10% of a member's income in order to be considered a fully "worthy" member. E.g. those who do not pay, cannot even go to temple to see their children get married.
Why do they enjoy tax exempt status if it is run by the "Corporation of the President of the Church of Jesus Christ of Latter-day Saints" and has big commercial holdings through various corporate entities? "In its home base of Salt Lake County, the church owns $137 million in commercial and industrial properties as valued by taxing authorities ...The Mormon Church's real-estate empire easily exceeds $1 billion, including farms and ranches in the West and Midwest, buildings and apartments on the West Coast and a huge chunk of land in central Florida", The Arizona Republic reported.
Tithing money supporting profits?



