>
> Christians celebrate their christianity on Sunday because it's the day Jesus rose, not because it's the Sabbath.
>
> Paul

They just happen to be combinable, but, correct me if I'm wrong, but it doesn't really matter. You're supposed to take off one day a week, whichever day that might be, for worship and rest, period. It just so happens that it's easier on churches and businesses if you take the same day off as everybody else.