Sunni/Shiite Hostility Old and New

In the reading, I read that Sunnis and Shiites were warring over their beliefs in the 1500's, and this is obviously seen today. By looking at the two situations side by side, it's amazing to see how much is different but yet they still seem to fight over the same problem. This leads me to believe that when it comes to religion, there is little that changes over time. The only thing that has changed in this religious war is how they are killing each other. They started with these beliefs when the Ottoman Empire had formed, and all they had then were spears and swords. But even after all these advancements in technology and science, Sunnis and Shiites still kill one another, but now use guns. I find this so barbaric that it sickens me. I'm constantly questioning why their old ways cannot be modified, because if they can move from spears to guns, can't they move from war to love?