Something holy or sacred, especially if it's related to priests, is sacerdotal. Some sacerdotal duties might include celebrating Mass and hearing confessions.
The religious adjective sacerdotal goes back to the Latin sacerdos, "offerer of sacrifices" or "priest." It's sometimes used to mean "sacred," and the two words share a root meaning "to sanctify," but it usually applies directly to priests. You might refer to the sacerdotal garments priests wear, the sacerdotal rites they perform, or the sacerdotal authority they hold within the church.