the people giving money to churches to attend that church, should pick up the cost of going to that church. which includes property taxes. if they are not willing to pay for that, it's their problem. excusing churches from these taxes puts the burden for the church not on its members, but on everyone.
let me ask you - that mcdonalds down the street. are it's property taxes paid by you? do you think if they declared themselves the church of fat asses, their property tax should be paid by you, as a county resident? because it would be, like it is for churches. when a portion of land isn't getting tax collected, the cost for the county doesn't go away - they get it from the people paying the taxes.