NoNukes writes:
Searching why Christians worship up on Sunday will uncover the fact that there are various answers given with no one really sure of the right one.
In Greek, Saturday is 'Σάββατο' (pronounced 'Savato'). You can see from the spelling that it shares word roots with the word 'Sabbath'.
I honestly don't recall the rationale for changing the holy day to Sunday. There are various Christian sects that actually celebrate Saturday as the actual Sabbath.
And probably a few pagan sects that are worshiping 'Saturn'. (aka 'Cronus')