I don't see how this law violates private property rights. If the church doesn't want guns on their property, all they have to do is either post a sign or verbally notify the congregants.
Could it be that these "chuches" - sic - want it both ways.
They want to ban guns but at the same time they want no visible signs or notices to that effect?
That would make them "feel" safe knowing that the criminals might not know, but at the same time disarming the congregation.
Some criminals still rob banks even knowing they'll encounter gunning resistance. If the congregation is disarmed the effect can still be just as deadly.