Yup, now we are talking close to equivalence.
The only real problem is that heretics are likely to still attract some sort of following among the faithful, so completely removing their abilities would seem odd, as is telling them to just find a new religion. This is the characters faith, their core belief (at least in most cases, surely there are priests characters that do not really believe in their faith) and yet they should be able to just convert to another religion?
It is far too much work at this stage, but a new system that sees the heretic trying to wage a guerilla religious war against the establishment would be entertaining.
In existing mechanics it's a matter of them getting a player following from the starting religion that can help them establish a new heretical sect.
