Churches are not allowed to be political and keep their 501C status.
Here's how to report them:
To: eoclass@irs.gov
Subject: Report of Illegal Church Electioneering
Body:
“To whom it may concern,
I am contacting you in regards to [Church name] for their partisan political actions despite claiming non profit status. They reside at [Full address]. Photo evidence of their electioneering is attached to this email in the form of a [Type of political advertisement] posted at/distributed from [Detailed location; i.e. SW corner of building]; photo taken [time and date].
Regards,
Full name, address, and contact information”
An article describing the process for communicating alleged exempt organization tax law violations to the IRS and how the IRS handles such information.
www.irs.gov
I found this information on reddit after a bit of digging around and used it a few days ago.
The church down the street has taken down their sign..