In Peter Geiermann's The Convert's Catechism of Catholic Doctrine

Historically, the Sabbath (Saturday) was the biblically mandated day of rest for the Jewish people. However, the early Christian community began to prioritize the "first day of the week"—the day of Christ's Resurrection—as the primary time for communal worship. According to the

, this transition is framed not as a dismissal of the Sabbath's holiness, but as a deliberate "transfer of solemnity" enacted by the Catholic Church. The Historical Context

focuses on the Sabbath, it is worth noting that in the universal Catechism of the Catholic Church

The catechism uses this specific point to illustrate the teaching authority (Magisterium) of the Church. The argument posits that because the Bible itself does not explicitly command a change from Saturday to Sunday, the shift rests on the Church's perceived power to interpret and apply divine law to the life of the faithful. For converts, this teaching serves as a pivotal lesson on the relationship between Scripture and Tradition. Divine Revelation and Natural Reason While page 50 of the Convert's Catechism

, page 50 traditionally addresses the Third Commandment, focusing specifically on the shift from Saturday (the Sabbath) to Sunday (the Lord's Day). The Transfer of Solemnity: An Essay on Sabbath and Sunday

The question of why Christians worship on Sunday rather than Saturday is a cornerstone of liturgical theology and ecclesiastical authority. In The Convert's Catechism