The Sabbath is one of the bone of contention among Christians. Sabbath was a covenant of God to Israel and should be handed down from generation to generation. In the Book of Exodus 31:16-17 God said, 16 The Israelites are to observe the Sabbath, celebrating it for the generations to come as a lasting covenant. 17 It will be a sign between me and the Israelites forever, for in six days the LORD made the heavens and the earth, and on the seventh day he abstained from work and rested.’ ”
Therefore, it is a day of the Lord, wherein Israel people should gather together to praise, glorify and talk about God. If Sunday is the first day of the week, then this should be Saturday. God said, that He worked for 6 days, and on the 7th day, He rest. God wanted us to do the same, but put the rest day as a day to worship Him. It is indeed, to be the day of the Lord. However, during the reign of Constantinople, when Christianity was declared as the national religion, they changed the Sabbath from Saturday to Sunday. Since Romans were pagans, they changed the Saturday to Sunday to still incorporate their worship to their Sun god which they do during Sunday. That’s actually the origin of the day Sunday, in honor of their Sun god. Among Christian church today, Sunday is the day of the Lord which is called Sunday Worship to include Sunday school (talk about words of God base from Scripture), Praise and Worship, and Words of God for the day. Actually Sunday worship today is align with today’s contemporary world wherein Sunday is the rest day of all working people. However, still according to God’s word, Sabbath should still fall on Saturday. Let us not forget that God is an Omniscient God who knows the past, the present and the future. As long as you will give one day for Him, you are still following and being obedient to His command.