Do you happen to know if any or all of those states allow individual churches to explicitly permit carrying on their grounds? Seems to me there would be a serious infringement on religious freedom if the state prohibited a church from allowing people to do on its grounds what they are allowed to do in most other locations. I can't imagine a challenge to such a no-opt-out prohibition would survive in court. Maybe a requirement to post prominently that the church DOES allow carry, since the state law would cause visitors to assume otherwise in the absence of such notice, but not an outright prohibition.
IIRC, GA allows for explicit permission.
Can make for an awkward situation, though, considering how polarized the issue is.