"Their religion drives them on. They have to fight until all are in a state of subjection to Islam. It's not them, it's the religion."
No. These are Sunnis killing Shias. It's called civil war, and basically an ethnic/territorial one. The attacks are overwhelmingly done by the more secular Sunnis against the more religious Shias b/c they want to prevent the Shias from gaining power- which will likely lead to an alliance with Iran. Religion plays a role, but these killings are not done to subject anyone to islam- they are all islamics.