While we are free to gather on any day to receive God’s blessings, we have chosen Sunday for a particular reason:
Sunday is the eighth day, that is, a new creation. Recall the story of creation. God finished creating the heavens and the earth on the sixth day. He rested on the seventh day. Then Adam and Eve fell into sin plunging the whole world into sin and death. Compare that with Christ. Christ finished the work of redeeming the world on Good Friday, the sixth day. He rested in the tomb on the seventh day. On the eighth day, He rose from the dead destroying death and restoring life to all people. So Sunday is not only the day Jesus rose from the dead, but it is the day of this new creation. We entered this day as a new creation through Holy Baptism and remain a new creation through Word and Communion.