Winger wackiness notwithstanding, the law does not prohibit any church from endorsing or opposing specific political candidates or parties. The First Amendment applies just as strongly in churches as it does anywhere else.
So the issue being raised by those ministers who are overtly urging the election of John McCain is not really the entalgment of religion and politics. The real issue is the entanglement of the federal treasury and political campaigns.
The government has chosen to exempt non-profit organizations such as churches from taxation. In effect, the exemption amounts to a subsidy of those organizations by everyone else. So the question is not whether a minister has the right to endorse a candidate from the pulpit. He certainly does. Rather, the question is, does the government have the right to compel me (and all other taxpayers) to subsidize that endorsement? If a church--or any other nonprofit entity--wants to endorse a candidate, it can. Just don't ask the government to subsidize that endorsement.