Disciplina arcani

Disciplina arcani (Latin for "discipline of the secret") was a custom that prevailed in the 4th and 5th centuries of Christianity, whereby knowledge of certain doctrines and rites of the Christian religion was kept from non-Christians and even from those who were undergoing instruction in the faith so that they may progressively learn the teachings of the faith and not fall to heresy due to simplistic misunderstandings (hence, doctrines were kept from catechumens, Christian converts who had not yet been baptized).