As an Atheists, I am not affronted, offended, upset, or even miffed for those who want to have a cross there. I don`t feel excluded.
If it helps people come together, to be charitable, to be good people, to help one another to see a cross there, to have the cross there why would that negatively effect me?
I as an atheist I actually feel that this group is fighting the wrong fight (if there's even a fight to be had)
FYI:
The USA was NOT founded on christian values, or as a christian nation. If a Christian nation had been the intent of the founders, they would have put that in the Constitution, front and center. Yet the text of the Constitution contains no references to God, Jesus Christ, or Christianity. That document does not state that our country is an officially Christian nation.
5 Reasons America Is Not -- And Has Never Been -- a Christian Nation | Alternet
The gov't does use Christianity to further it's agenda. But not from belief in it, but as a tool to control its populace.