ANGOLA, La. — Like most of his fellow inmates, Daryl Walters, 45, can expect to spend the rest of his days in the infamous prison on a former slave plantation here. He was sentenced to life without parole for a murder more than 20 years ago in a state where a life sentence means just that.

Yet there he was on a recent evening, preaching the Gospel to 200 men in a spired church in the heart of the Louisiana State Penitentiary, talking salvation and joy to murderers and rapists and robbers who waved their arms to an inmate band’s Christian worship music.

“God is merciful,” intoned Mr. Walters, an assistant pastor at one of many churches scattered through this maximum-security prison, informally known as Angola. “God gives us so many benefits.”

Mr. Walters is a graduate of one of the most unusual prison programs in the country: a Southern Baptist Bible college inside this sprawling facility, offering bachelor’s degrees in a rigorous four-year course that includes study of Greek and Hebrew as well as techniques for “sidewalk ministry” that inmates can practice in their dorms and meal lines.