Father Santora shows up for one scene. So he's kind of minor, but he plays an important role for Perry, because in his one scene, he warms up Perry to religion. He even gets him to pray.
Like Brew, Father Santora is an honest religious figure. He doesn't pretend to be overly holy. He admits that "I'm not quite ready to die either" (17.68), and that prayer won't necessarily keep Perry alive.
Father Santora seems a bit mystified and confused by the war. After praying with Perry's platoon, he says, "How come all these places over here have such foreign-sounding names?" (17.85)
Well, the fact that they're in a foreign country and the names are from another language could have something to do with it. Maybe Father Santora hasn't travelled much.
But his honest, everyman strategy really works on Perry. At this point, Perry's up for anything that will make him feel better. Prayer, for him, isn't about being pious. It's about trying to feel normal, which is an important way to survive.