"Novice" doesn't originally have religious roots; in the story of its etymology, it got sidetracked into religion.
Quite likely because the only dudes who knew Latin in the Middle Ages were in monasteries, and so they applied Latin words they learned to their circumstances. "Hey, it says here that when Romans brought in a new imported, inexperienced slave, they called them novicus. Let's use that for our newcomers! After all, we make them do chores, like slaves, LOLZ!"
Quite likely because the only dudes who knew Latin in the Middle Ages were in monasteries, and so they applied Latin words they learned to their circumstances. "Hey, it says here that when Romans brought in a new imported, inexperienced slave, they called them novicus. Let's use that for our newcomers! After all, we make them do chores, like slaves, LOLZ!"