steeplejacking

Subversion of Churches by Theocratic religious groups who could not gain much if their agenda was open. They use many of what has been thought of as Communist Subversion techniques.

There is more detail here.

Great neologism! I know that a steeplejack was a person who climbed such towers to repair them, but I've never heard of this form of the word.

The takeover of a mainstream religious denomination by a group of radical extremists. Coined, as far as I can tell, by this book.