Catholic priests cannot be good priests and good teachers in the same instance of time. Before you go on about my craziness, reread that sentence. Catholic priests cannot be GOOD priests and GOOD teachers at the same time. The reason for this is simple: priests and school teachers have generally opposing philosophies.
For example, a good Catholic priests shows mercy. Good teachers are merciless. A good Catholic priest is patient. Teachers need to be efficient. Good priests are happy when you repair your past mistakes. Good teachers give zeros. Good priests are humble. Good teachers "know it all".
Simply, priests must strive to be like Jesus. But in today's competitive society, being passive leads one nowhere. Confucius taught that teachers must love discipline (that is, the action). Good priests are about forgiveness. Good teachers are about taking responsibility through punishment.