This is one of the most ridiculous slanders against the Church because it clearly betrays any knowledge of the Sabbath, the Mosaic Law, or the Holy Sacrifice of the Mass.
The Sabbath and the Mass are not the same thing. I know the modern world, thanks in no small part to Protestantism, has largely done away with any significance in the Lord’s Day and the Mass, but it remains that the Mass is the only way to offer proper sacrifice to God and it is done on Sunday because that is the day Christ rose from the dead. It has been offered on Sunday since the very first Easter Sunday and was continued by the Apostles after the Ascension of Our Lord and has been ever since.
The Sabbath was the day set aside for Jews to offer prayer and worship to God once per week. The Mass is the re-presentation of Christ’s perfect offering of Himself to the Father for the forgiveness of sins. It is, as the Church says, the source and summit of the Christian life. It is the most holy and efficacious thing a Christian can do. It is offered on Sunday in rememberance of the Resurrection of Christ and His victory over death.
To say “the Church changed the sabbath from Saturday to Sunday” is just flatly nonsensical because they’re not the same thing. The Sabbath is Jewish Mosaic observance which is not to be observed by Christians because the Mosaic law has been fulfilled in Christ.
The Church has the authority to set the date of mandatory attendance of the Mass because of her power to bind and loose (Matthew 18). Binding and loosing is a Hebrew phrase which roughly means the authority to allow or forbid things. It is by this administrative authority that Christ gave His Church which allows Her to determine when the appointed day of worship is. If She determines it is Sunday, then that’s the day it will be. Bound here on earth, as well as in Heaven.
Please research this issue because to make such an accusation betrays a lack of knowledge of the topic.