What has Christianity truly contributed to humanity

[Bucky Ball]

Also, as a musician, here's something I appreciate that was inspired by Christian faith:

Bernstein used to say that the apex of Western Civilization were the quartets from Fidelio, and the the quartets from the last movement of the 9th symphony, (which I could never see)
I do think the Sanctus and Benedictus from the Missa Solemnis may fit THAT bill, but only because I've accompanied it with a good choir (and San Diego Symphony). 
Western music really is not the possession of the religious. Many musicians who were not any sect wrote music for the church, as that was the only way to make a regular income.