Here is my theory why there are so many churches in USA?
1. Religion is a very good business. First, it is tax free. Second, there is no lack of "volunteers" working for you. Third, USA has a very large customer base.
2. There are basically two products religions are selling: hope and fear. Different church has a different combination of them - a different formula so to speak. Those successful would gain great wealth and power. Some churches add a little welfare as a side business.
3. "False christians" has become a caveat. It means customers of the churches other than yours.
4. The initial hurdle to start such a business is minimum. One just needs to give the bible a slightly different interpretation and starts talking up one's interpretation as the "true" meaning. The wonderful thing about christians in that the bible contains such many contradictions, inconsistencies and falsehoods that even the most stupid interpretation would fix into the bible. Even better is that one does not have to justify one's claim. - "Its all from God and I have a direct line with him" is sufficient. The catch is that you need to sell your soul to Satan.
[I know this post will offend a lot of people. So be it. Just name me a preacher who works full time in a real job and then use the money earned in the real job to preach. Successful preachers are paid handsomely by the "church" (his own business which does not pay any tax) and spend like a king.]