That monument is a grave which has the religious orientation of those memorialized marked as atheist. It is no more an atheist monument than a grave of a shoemaker is a monument to shoes.
The difference is that while bad things were done in defence of Christianity, I can think of any amount of positive accomplishments in the name of Christ; can you think of anything positive that was accomplished in the name of atheism?
So when a Christian does good deeds, that's "in the name of Christ", but when an atheist does good deeds, that's by your definition never in the name of atheism? Has it occurred to you that most atheists aren't interested in doing things "in the name of atheism"?
Have you ever considered the possibility that atheists do good deeds because they think that it is the right thing to do, and not something that they need to do in order to "validate" their atheism?
And you can substitute "atheism" for any other -ism or belief or religion or tendency you can think of. The same principle applies: just because you center your entire belief system around a religion and try to "validate" it in certain ways, does not follow that everyone else behaves the same way or thinks they have something to prove in this regard.
I'm not an atheist myself, but I always am amused by those who set out to "prove" that only theists can be moral, good, rational, or what have you. It's a profoundly blinkered point of view, and does not help the public image of Christians or other theists who argue that way. It makes them look rather silly, in fact, to those who have eyes to see how real people - atheists and Christians alike - actually behave. Most atheists aren't leftist Marxist totalitarians, just as most theists aren't fundamentalist religious terrorists.
I knew I should not have clicked on this thread. This is a topic that sheds more heat than light; just igore me. I shouldn't have come in in the middle of this conversation.