This analysis of freedom of religion and the Establishment Clause is flawed b/c it is only partially correct. Churches are able to influence public policy. The Roman Catholic Church has every right to discuss how abortion is murder of a human. Mormons are free to tell people they can be god on another planet, hopefully in this universe. Witnesses can teach their stuff and tell people not to vote.
A broad spectrum of political activity is allowed. Every election the press reports sermons that leave absolutely no doubt which candidate to support. What is restricted is "Vote for X? or "Register as Z."
Nostonecutters assertions concerning forced coercion are wrong. See Constantine's Sword, a thick best selling book dealing with antiSemitism in the church, written by someone with strong church ties.