As the cliché goes, the Church of England is just the Tory party at prayer, and the religious origins of modern Conservatism can be found in Methodism - Thatcher was born in the heart of Wesley country.
It was no coincidence that Thatcher's first rant was a sermon on St Francis.
Methodist ideology is still at the heart of Tory 'pull yourself up by your own bootstraps' beliefs.
So it follows that religion would be the most potent weapon when attacking the Tories and they always squeal the loudest when the church is doing the attacking.
It is always the best strategy to attack a political system by judging it on its purported values.
I think I might just disagree on the Methodism / Conservatism links.
Now all sorts of people can claim all sorts of roots and backgrounds, inspirations and common ground. But in my experience of working with Methodists I'd have to say it's rare to meet a tory Methodist. The mantra, as far as I can tell is to be nice and loving to others by giving services freely and offering help. This help might be free soup, free use of halls and other spaces, free places on buses to protest about this weeks thing.
I don't see that link in real grass roots life. Can't speak for many others, but in my experience those little Protestant sub churches, the likes of URC and whatnot are most definitely 'left' in the way they operate.
Certainly locally, those independent Wesleyian type churches are the first place to go when somebody wants help promoting a broadly softly lefty project.