The thing is, what they often call religious wars aren't, instead they were just wars about power and influence. The kings would come up with a "Holy" purpose for attacking another country or group of people to protect or extend their power.
The soldiers in almost every war mentioned weren't fighting because they were Christians or Muslims, they were fighting because they were either made to fight or because their families were starving to death, so they took a job in the army so they could better feed their loved ones.
Most organizations that help people in need are Christian based. We need more of these people, so we can help our brethren more not less. Atheists' organizations don't generally focus on the needs of others in their community. Not that there aren’t great, caring, people who are atheists, but the bottom line is they don’t generally come together to help people with clothing, food, and/or shelter.