A Line in the Sand — K.A. Stewart

AN ACT OF FAITH Jesse James Dawson is a husband and father who never intended to be the guardian of 275 extra souls, or to find himself in the middle of a demon war. When that war comes right to his front door, endangering his family, he is forced to seek aid from the last people he ever wanted to ask: the Catholic church and the priest sent to protect him, Cameron. The Order of St. Silvius is made up of warrior-priests, operating out of its home base in Vatican City. The holy order has been facing off with demons for centuries. In a city as ancient and steeped in magic as Rome is, a few centuries is plenty of time to hide a few secrets, and what Jesse and Cameron don't know could get them killed.