James Martin, the best-selling author of Jesus: a pilgrimage and  The Jesuit Guide to (Almost) Everything, is probably the most popular priest in the US. His debut novel might be compared to Paulo Coehlo’s popular fiction, perhaps even to the weightier Siddhartha from a few generations ago, except that it is definitively Christian and without any pretensions.The story of Anne, Mark and Fr Paul takes place in and around a Trappist monastery in present-day Philadelphia suburbia. Mark, 30, is single, an underemployed ex-architect now handyman at the monastery. He is kind, good-looking and has a problem with ­commitment, having too much casual sex with the women he dates. His landlady, Anne, 40, is divorced, an accountant, and grieving the death of her 13-year-old son. Mark&rsq