Should freedom of religion apply to all religions?
Up to the point where laws are broken.
Freedom of religion shouldn't mean that you can take what ever liberty you want away from other people. Don't drink the Koolaid folks
Any religion, yes.
Not necessarily any religious practice.
Let's say, hypothetically, a cult of Christianity forms that believes the consumption of the Eucharist requires the eating of human flesh to be valid.
They can believe that all they want.
They can't eat human flesh.
Normally I'd say "unless it was consented to by a person of sound mind and consenting age" but that gets tricky when dealing with the wills of all-powerful deities.