I would approach this issue from a different angle. Charities have to provide 'proof' that they've done actual work to get their tax break. Religions don't. The only time a religion should receive a tax break is for their charity work.

Tax breaks just because something is called a religion does nothing for society as a whole and is a magnet for con-men.

Politics is a different matter. Politics permiates everything - which is why this 10% rule is so selectively dangerous for charities. Government can now pick and choose which charitable organizations to delist. I'm sure this threat will go way beyond environmental groups.

Tax breaks for political party donations are supposed to encourage citizens to participate in the process, including those of modest means. At least in the political field there is a means to judge if a particular philosophy or direction is a success. They're called elections. A process alien to most religions.