The churches, non-partisan (cough, cough) are allowed to help transport people after church to the polls.They call it Souls to the Polls.
The constitution does not support the separation of church and state. If a church wants to bus people to the polls or if a pastor wants to endorse a person or party, they are free to do so under our constitution. Unfortunately, the constitution is ignored or bastardized far too often.
Prior to 1954, churches and non-profits had no restrictions on their freedom of speech or their right to speak out in favor or against political issues or candidates.
I believe H.R. 2357 was that law that punished 'political' speech and activity in churches.