The nun is certain, or says she is, that the priest is molesting one of the students in her school, but we never are so sure, thanks to John Patrick Shanley’s exquisitely well-crafted play, which debuted on Broadway in 2005, winning both the Pulitzer Prize for Drama, and four Tony Awards, including Best Play. In this first Broadway revival of “Doubt: A Parable,” which is running only through April 21 at Roundabout’s newly renamed Todd Haimes Theater, the deceptively simple script holds up, the production is sturdy, but only one of the four performances is superb. The others are serviceable, in roles made indelible in the original production (especially Cherry Jones as Sister Aloysius) or in the 2008 movie (Philip Seymour Hoffman as Father Flynn.)