Romans 14
5One man considers one day more sacred than another; another man considers every day alike. Each one should be fully convinced in his own mind. 6He who regards one day as special, does so to the Lord. He who eats meat, eats to the Lord, for he gives thanks to God; and he who abstains, does so to the Lord and gives thanks to God. 7For none of us lives to himself alone and none of us dies to himself alone.
Pretty clear what Paul is saying here. Or do you have non-scriptural arguments for why these words don't apply to how different people go about worshipping the Lord...?
You are seriously telling me that the Sabbath day is not set apart...