Here is my question for you all to wrangle over. Can someone who does not believe in or practice keeping the Sabbath be considered a Christian?

Please explain your answers. For those who answer yes, could those who continually and in unrepentance practice idolatry, murder, adultery, coveting, lying, etc. (the other 9) be considered a Christian? If you have two different answers to these questions, how is the Sabbath not as important as the other 9?