"Remember the sabbath day, to keep it holy"

* Deliberate failure of the Sunday obligation—The Christian Sunday (the Lord’s Day) celebrates the new life of the world born in Christ’s Resurrection. All humans have a duty, to praise God and give him thanks. Thus all Christians are bound to participate in the Mass, and must partake of the Eucharist at least on holy days of obligation. Deliberate failure to do this constitutes a grave sin (CCC 2181).