Actually, the commandment is not to have any other God besides God. Atheists actually do this quite well, as they don't believe in any deities.
Atheists do not worship idols either, so they probably do better on this one than Christians. They don't believe in any supernatural deities, including idol worship.
It would be incredibly unreasonable for God to judge atheists for not keeping the sabbath when they do not believe that scripture has any merit whatsoever.
Christians do this just as much as atheists. And, it's a lot less worse when atheists do it, as they don't believe that God exists in any way shape or form. So they don't think they are offending anything.
This is just patently false. Atheists and Christians alike say "swear to God" just as much. And, dishonesty is not something that is directly associated with atheism or christianity in any way. So, it stands to reason that this is a toss up, violated by both atheists and christians in more or less equal amounts. And, don't forget that it would be unreasonable to expect someone who does not believe in God to follow his law beyond being honest.