I think there are rules for churches pertaining to renting out their spaces (just like schools). If a church regularly rents out its space for events and they rent to everyone (the public)..... as long as the organization renting the space pays to going rate (not a discounted rate)...then the church can rent to a political group, they just cannot endorse/sponsor the event. Same as schools renting out their spaces to the public. Sometimes schools rent to churches for events. It is legal as long as the church pays the school the going rate and the school does not endorse the event. I found this online:

Question: On occasion the church rents space to outside groups to meet using the church’s facilities. Can the church rent space to a political candidate?

Answer: Yes, with conditions:

The church’s usual and customary fair market rent needs to be charged.
(Note: this can raise an unrelated business income tax issue for the church.) and;
The space needs to be available to candidates in the same election on an equal basis and;
The renting of the space must be an ongoing activity of the church.

It works great for him when he controls the IRS even though he has been under audit for years and has made many promises to allow churches to be politically active and retain their tax exempt status. We can rarely get these fake church tax scams investigated for overt fraud so their is zero chance of nailing them for illegally pandering to King Trump.

Never up the GOP will officially register as a church and collect all their dark money tax free.

I think it fair to say it's not the first time a candidate or president had event(s) in a church.