Time Travel - What is a Mystery

PAROCHIAL SCHOOL, DANBURY, CONNECTICUT - 1950

What is a Mystery?

A mystery is a truth which we cannot fully understand. 

Why must we believe the mysteries of religion?

We must believe the mysteries of religion because God, who can neither deceive nor be deceived, has deigned to make these truths known in part to us. 
"Blessed are thy that have not seen, and have believed." John 20: 29.

Advanced Catechism of Catholic Faith and Practice, 1922.