Should Christians still worship on the Sabbath?
As Christians, we are not under the law that requires the observance of the Sabbath. It was strictly a covenant between God and the Jews that was a precursor of the salvation that Jesus Christ would eventually bring to humanity. Paul said if you try to keep the law, you have fallen from grace.
"Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace" (Gal. 5:4).
"Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law [is] the knowledge of sin" (Rom. 3:20).
"But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not [in] the oldness of the letter" (Rom. 7:6).
The Law was imperfect, but Christ became the perfect fulfillment of the Law. We are to honor God with our whole lives every day of the week, not just on one day. We are to celebrate His resurrection continuously, not just on Sunday.
Colossians 2:16-17 says, "Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. These are a shadow of the things that were to come; the reality, however, is found in Christ."