Because the first American revolution was started in churches with the assembly and gathering of like minded people discussing political issues of the day. LBJ pushing his liberal agenda knew that it had to be stopped so he created the Tax laws that will strip a church of its tax exempt status if they do any of the 1st, or 4th amendment activities relating to politics - unless they are non-white or non-christian.
So yes its a federal gag order on white Christian churches to discuss nothing politically or get fined massive tax dollars.
I have to look into it again but there was a Constitution seminar for pastors, at my church a while back informing them of what they can and can’t do and say. They can do a lot more than they apparently are willing to do. I call them cowards. The former pastor of our church was not a coward but when he had to retire for health reasons his replacements have not lived up to his standards. Some of the people I go to church with are trying to carry on his legacy, me included. Not in running for office, but getting involved in the community affairs (speaking for myself) others have run for office successfully. But for the most part the church has let itself be shut down. There is very little boldness.