What happens when a former US Marine becomes a Franciscan friar and then goes on to found a monastery in the toughest district of Ireland’s toughest city? In 2007, Father Sylvester and a small group of American friars from the Bronx, N.Y., did just that when they arrived in Limerick, Ireland. They left behind their former lives as a teacher, a soldier, a punk-rock singer, and a rapper to transform lives through prayer. The urban district they live in, Moyross – a sea of burned-down and boarded-up houses – is always in the news for the wrong reasons: drugs, shootings,...