The bible teaches that we should not change the words of God in the bible by adding to or subtracting from the words. We have to consider the words of God as absolute and should accept the words as it is written in the bible. Especially, when we talk about the commands of God, we have to be very careful not to add our opinions to them.

Revelation 22:18 I warn everyone who hears the words of the prophecy of this scroll: If anyone adds anything to them, God will add to that person the plagues described in this scroll. 19 And if anyone takes words away from this scroll of prophecy, God will take away from that person any share in the tree of life and in the Holy City, which are described in this scroll.

God clearly teaches us that we should not add to or subtract from the words of God. Therefore, when we keep the commands of God, we should not change anything from those words.

Then let us think about the day of worship. When is the day of worship according to the words of God in the bible? In Genesis, we can see the creation work of God. God created everything from the first day to the sixth day. And on the seventh day God took rest and he set the seventh day as the Sabbath Day, the day to commemorate the creation work of God. And God commanded to keep the Sabbath Day holy.

Exodus 20:8 “Remember the Sabbath day by keeping it holy. 9 Six days you shall labor and do all your work, 10 but the seventh day is a sabbath to the Lord your God. On it you shall not do any work, neither you, nor your son or daughter, nor your male or female servant, nor your animals, nor any foreigner residing in your towns. 11 For in six days the Lord made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the Lord blessed the Sabbath day and made it holy.

In the New Testament, Jesus and his disciples also kept the Sabbath Day according to the laws of the new covenant by worshiping God in spirit and in truth.

Luke 4:16 He went to Nazareth, where he had been brought up, and on the Sabbath day he went into the synagogue, as was his custom. He stood up to read, 17 and the scroll of the prophet Isaiah was handed to him.

And the Sabbath Day is Saturday in today’s calendar. Therefore, the day that we should go to church to worship God is Saturday, not Sunday. Even the Catholic Church which originated the Sunday worship states that the biblical day of worship is Saturday, not Sunday. And the Sunday worship does not have its origin in the bible, but in the doctrine of the Catholic Church. It means the Catholic Church added their own idea to the words of God. They added the Sunday worship and subtracted the Sabbath worship.

Third—A rule of faith, or a competent guide to heaven, must be able to instruct in all the truths necessary for salvation. Now the Scriptures alone do not contain all the truths which a Christian is bound to believe, nor do they explicitly enjoin all the duties which he is obliged to practice. Not to mention other examples, is not every Christian obliged to sanctify Sunday and to abstain on that day from unnecessary servile work? Is not the observance of this law among the most prominent of our sacred duties? But you may read the Bible from Genesis to Revelation, and you will not find a single line authorizing the sanctification of Sunday. The Scriptures enforce the religious observance of Saturday, a day which we never sanctify.

From “The Faith of Our Fathers” by James Gibbons

They clearly reveal that the Sunday worship is not biblical at all. The day of worship in the bible is Saturday. They added a Sunday worship to the words of God, and subtracted the Sabbath day from the words. They make many excuses to justify their lawless practices. What they are doing, however, is just lawlessness. They are adding plagues to themselves and taking away the tree of life from them. We have to be careful in following the teachings coming from man.

Christ Ahnsahnghong and Heavenly Mother restored all the laws of the new covenant. When we hear a teaching about the faith, we have to test the teaching through the words of God. If a teaching is not from the bible, then we should not follow the teaching. Those teachings come from man and they cannot give us salvation.