I agree 100% with Phizzy. All religious organizations should pay taxes like any other business. That includes contributions they receive, property they own, businesses they run, etc., etc. I also agree that true charities that actually help people should remain tax-free, even if they are run by religious groups. This should NOT include organizations that hide behind the false cloak of a "charity" like the JWs do in the UK. Their "educational" work is not charity in any sense. It is only given to those who accept "Bible studies," and then only as long as the person accepts JW dogma without question.
Also, all religious organizations as well as charities should be required to make their financial statements and tax returns public so people can see exactly where their money is going. The government could do that right now without much of a social upheaval. There is absolutely no reason why any tax-free organization should not have to disclose its financial information.