Atheists aren't the only ones. There's pleeeenty of arrogant religious folk out there.
That whole Ten Commandments thing in public places is a weird issue. The people in favor of it seem to think that a sign that has "don't kill" among its words will prevent kids from killing in school, or that the commandments will somehow prevent people from lying under oath in court.
The christmas tree thing - yeah, that was just stupid. Heck, here, my parents and I are atheists, and my sister is still unsure - atheist/buddist. We have a Christmas tree every year; we do the whole Easter thing - eggs, candy - well, used to. Getting older, and a financial crunch for our family have staved it off a bit this year. Going to see what's on sale tomorrow.

Heck, I'm even ok with allowing various versions of the Bible, Koran, and other holy writings available in public or school libraries.