The Atheist Contribution to World Civilization

I find myself becoming somewhat weary of opponents of Christianity and of religion in general who point to its flaws but offer no appreciation of its strengths, who criticize its failures but make no mention of its successes.

I thus wish to offer an open post today in which I ask a question: What is the atheist contribution to world civilization? What have atheists offered that was not offered before them by philosophers who believed in some sort of God, by Liberal Christians, by Deists or Pantheists or others who have some God concept as part of their worldview?

Please post your answers as comments, and feel free to use that forum to discuss the answers that have been given.

Hopefully the focus can be kept on this specific question, without getting sidetracked into the shortcomings and negative contributions that any impartial observer would acknowledge exist on all sides.