White churches are the most frequent targets - and crime is often the motive.
Three torched churches were discovered in Alabama Tuesday - the latest in a string of suspected arsons that damaged five churches in Bibb County.
Investigators have not discovered any apparent motives. Four of the five churches in Bibb County - three of which burned to the ground - were white Baptist congregations. The other was black.
Nationally, such patterns are not unusual. Most arson targets are white congregations, whereas mosques and synagogues get hit in much smaller numbers.
In a country with more than 350,000 churches, motives are as varied as the denominations they target, experts say. According to the Insurance Information Institute, the top reasons for torching a church include the coverup of a burglary, vandalism, and revenge. Racism, insurance fraud, and thrill-seeking are less common.
In fact, church burnings are common. The nation sees 15 to 20 church arsons a month, scattered from Florida to California. [Editor's note: The original version misstated the frequency of church burnings in the US.]
Nearly 1,000 churches burned between 1996 and 2000 nationwide, according to the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF). Authorities nabbed about 100 suspects, a pace that has only decreased slightly.
Since the summer of 1996, when a spate of racially motivated Alabama church fires drew national attention, investigators are not much closer to knowing what fuels the church arsonist. Confessions range from the hateful to the mundane: In Suffolk County, Va., an 18-year-old pleaded guilty to torching St. Mary's Catholic Church in October 2005, after stealing a few hot dogs and some sacramental wine in the course of an inebriated evening.