Introduction I grew up in a church that believed that Sunday was the New Testament Sabbath. We went to church on Sunday and we regarded Sunday as the Sabbath. To us, the 4th commandment was speaking of Sunday.

When I decided to read through the Bible myself, I couldn't help but notice that the Shabbat was the 7th day, that is Saturday, and there was nary a mention of a Sunday Shabbat for Christians. Still, it never occurred to me that I should be keeping Sabbath on the 7th day because to me Sabbath and Church were synonymous and Church was on Sundays.

But do you see something wrong here? The fact that the Sabbath is on the 7th day is so obvious that even a teen-ager giving the Bible a casual reading can see it. There's no mystery. It's not some hidden or secret knowledge. It is one of the Ten Commandments! Something peculiar is going on here...

http://www.rabbiyeshua.com/articles/2001/sundayintro.html