I feel that a very important distinction must be made between ORGANIZED RELIGION and GATHERINGS OF A RELIGIOUS NATURE.
When it comes to GATHERINGS OF A RELIGIOUS NATURE, people should be permitted to practice whichever religion they'd like, so long as...
1) There's complete transparent-ness in their activities.
2) It is done in a private area designated for religious purposes or, failing that, in a private residence (i.e. it doesn't become a cult).
3) They allow followers to come to them, rather than soliciting others.
4) They come up with their own funding if they would like to establish a church, mosque, temple etc.
5) The religion does not in any way require the sacrificing of children, animals or people.
When it comes to ORGANIZED RELIGION, I feel that it should be constitutionally bound to never be permitted to exist within the same sphere as politics, and religious organizations of all shapes and sizes should not qualify for any sort of tax-free status. They must either pay taxes like every other organization, or tithe their followers.