### Instruction: Q. 390. Is it a mortal sin not to hear Mass on a Sunday or a holyday of obligation?

### Response: A. It is a mortal sin not to hear Mass on a Sunday or a holyday of obligation unless we are excused for a serious reason. They also commit a mortal sin who, having others under their charge, hinder them from hearing Mass, without a sufficient reason.

-- Source: Baltimore Catechism #1 / LESSON THIRTY-FIRST ON THE FIRST AND SECOND COMMANDMENTS OF THE CHURCH / Q. 390