My friend it’s not what you believe that matters but what saith the LORD is what matters. When you look at Isa. 58:13, God talks of the Sabbath as His holy day. There are 7 days in a week, out of them, it’s only the Seventh day (Sabbath) which has been blessed and made holy. Pls read it, it has a lot of details about the Sabbath.
Second, do you believe in good Friday? Then according to John.19:31 Jesus Christ was killed on the preparations day which was on Friday and the next day was the Sabbath. Now which day follows Friday? It’s Saturday. Since man gave names to days. There has not been a revision of days i.e to call Tuesday Wednesday or something like that and thus Sabbath remains on Saturday. But Papacy changed the Sabbath from Saturday to Sunday and labeled the Sabbath day Saturday, as for the Jews, and that Christians worship on Sunday. God foresaw this happening and warned us about it in Dan.7:25. Jesus said in Mat.5:17, that He didn’t come to destroy the law or the prophets. But to fulfill. So my friend, Saturday remains the Sabbath day. Christ rose on the first day of the week look at Luke.24:1 and Mark.16:9(assuming that your Bible has that verse coz Satan has corrupted the Scriptures using his proxies on earth to continue to deceive the
children of God with false theology. I plea to you that you join the Sda Church which is mentioned even in the Bible in Rev. 12:17