There's a double standard here, though.

Tax-exempt charities are prohibited from using tax-exempt funds to engage in certain kinds of political speech. Those that do electioneer or conduct lobbying, for example, have separate non-tax-exempt branches that handle it, with their own funds and strict financial firewalls separating them from the rest of the organization.

Churches, on the other hand, get to flout those rules all the time. And I do mean churches; other religions don't tend to enjoy quite the same latitude.

And that selective enforcement by the government is a separation of church and state issue.