To keep a day holy means to keep it pious, godly, and sacred.

Catholics do keep the day holy. The day is consecrated to God by definite duties of religion. Innocent recreation does not desecrate it. Eating one’s meals on Sunday is not in itself a pious act, yet it does not desecrate the day. To keep a day pious does not mean that every single act must be one of piety. Any act which is not sinful can be offered to God’s greater honor and glory, even as David offered his dancing before the Ark of the Covenant. When the Pharisees complained to Christ that the disciples were doing what their traditions held to be unlawful, Christ replied that the Sabbath was made for man, not man for the Sabbath,

Radio Replies Volume 1 by Rev. Dr. Leslie Rumble MSC and Rev. Charles Mortimer Carty