If God gave us the day of rest being Saturday why do so many people go to church on Sunday, which was founded by the emperor of Rome, Constantine, in 321?

There is no verse in the Bible that made this change, so I came to the conclusion that we are following an old tradition or custom which the Bible tells us to watch out for.
 

Introduction
  The purpose of this, is to answer the question as to whether Christians should keep the Sabbath.

  • "Sabbath" refers to the 7th day of the week -- Saturday.
  • The 10 commandments are quoted in the panel alongside. The 4th commandment deals with the Sabbath.
  • To read an overall discussion of the 10 Commandments, Click Here. [When you're done, use your browser's Back Button to return to the page you are now reading.]
 

The 10 Commandments of God

  • 1. Thou shalt have no other gods before me.
  • 2. Thou shalt not make unto thee any graven image.
  • 3. Thou shalt not take the name of the Lord thy God in vain.
  • 4. Remember the sabbath day, to keep it holy.
  • 5. Honor thy father and thy mother.
  • 6. Thou shalt not kill.
  • 7. Thou shalt not commit adultery.
  • 8. Thou shalt not steal.
  • 9. Thou shalt not bear false witness against thy neighbor.
  • 10. Thou shalt not covet.

Summarized from Ex 20.1-17

 
Please also refer to Sabbath Keeping