It's often interesting to look into different belief systems. A trip to Church of Saint Peter in Gallicantu is a fantastic way to experience one of the local religions.
You'll have no end of sightseeing choices in Jerusalem. Church of Saint Peter in Gallicantu is a good place to begin here, but there are numerous other worthwhile sights to consider. Western Wall, Dome of the Rock, and Temple Mount are not far from the house of prayer and will fill in your day nicely.