Roman Catholic prelates in Michoacan state at last have drawn a line against local gangsters, and the officials nurturing them, further entangling what already was one of Mexico's more intractable knots of violence. But most of the Church hierarchy still seems reluctant to take a strong stand. The bishops have jumped in as the homegrown Knights Templar gang squares off against civilian militias, rival gangsters and thousands of federal troops across the Pacific Coast state.