Not many churches have security, but some of the larger ones do. Especially if the pastor is "famous" because of a radio show or a book or something he/she has done. You'd be surprised the number of oddballs a church service attracts. We have had drunk people wander in during the service and walk right up to the pastor who is speaking on the stage. There have been a number of hate crimes in churches as well, including people coming in and shooting the minister.
Good point. I just had never heard of it prior to this. Again I don't have much exposure to churchs....not that I don't have a faith just don't attend a church.