From CNN: The truth about church shootings.  Some excerpts:

“… Drake cautions against over-interpreting the increase in church shootings. People of faith are not being targeted because of their religion, he said. Rather, the shootings are part of an overall — and alarming — increase in mass shootings within the country at large.

In some ways, Drake said, houses of worship are simply the most “convenient venue” for attackers who harbor grudges against former lovers, spouses or friends. Many sanctuaries have regular schedules, lack robust security and proudly bear open-door policies. They are designed to attract the least and the lost, and to welcome them into a loving community, even if that sometimes has terrible consequences.”