Saturday is still the day on which God rested in the Christian calendar. The significance of Sunday comes from Jesus' resurrection. It wasn't until the Middle

Saturday is still the day on which God rested in the Christian calendar. The significance of Sunday comes from Jesus' resurrection. It wasn't until the Middle Ages that Sunday came to be treated as a "rest day" and therefore conflated with the idea of a "Sabbath" (see http://en.wikipedia.org/wiki/Lord%27s_Day http://en.wikipedia.org/wiki/Lord%27s_Day ). Even then, Sunday was generally termed the "first day" -- note that "Seventh Day Adventists" hold their religious services on Saturday.