catechism (en)

a summary of the principles of Christian religion in the form of questions and answers, used for the instruction of Christians

recondite (en)

(adjective) hidden from sight; concealed / (adjective) difficult or impossible for one of ordinary understanding or knowledge to comprehend; deep / (adjective) of, relating to, or dealing with something little known or obscure

theodicy (en)

(noun) defense of God's goodness and omnipotence in view of the existence of evil