[quote=@Andreyich]
Which really can only be answered from a supernatural point of view. 
[/quote]

These are not real explanations. I think it is entirely possible that we can get people to change their mindset from 'God Did It' to well that is interesting, lets investigate and find out the answer, just like every scientific discovery in history.

[quote=@Andreyich]
Hedonistic excess was an attempt as an answer before but the people of this excess generally were "weaker" and lead to their own downfall;
[/quote]

Sure you will always be able to tell people that they can get their eternity in paradise if they kill the infidel and motivate them to fight. 

[quote=@Andreyich]
We [u][i][b]might[/b][/i][/u] some day outgrow organized religion but spirituality will never, ever really disappear. 
[/quote]

I'll take killing organised religion. It might be impossible to eradicate the lucky rabbits foot or whatever other spiritual practice you want to name. Some spiritual practices, such as meditation, might eventually be moved into the realm of science.