Wow. This is effectively asking, "please give an example of violence in History". You'd be hard-pressed to find any example of religious violence that didn't have some kind of cultural-ethnic underpinning.
One of my favorite examples is Arianism. This was a difference with the Pope in Rome over the precise nature of the Holy Trinity which even most devout Christians are hard-pressed to explain.
However, when German tribes were conquering the western half of the Roman empire, having a slightly heretical faith became rather convenient. It allowed them to still effectively be Christians to their new subjects, but to not have to subject themselves to the authority of the Pope. In other words, it allowed them to keep their separate identity as Germans.
Once they became established (and amalgamated into the local population), they generally dropped Arianism.
Moving to more recent history, I'm sure most of you know about the big kerfuffle between the Catholics and the Protestants in Northern Ireland. What isn't typically reported is that the Catholics there are typically descended from native Irish peoples, while the Protestants are descendents of Scottish folk who migrated to Ireland centuries earlier.
There are of course oodles of modern examples. For instance, East Timor: Catholic (to Indonesia's Muslim), but also Tetum-speaking where Indonesia's official language is a flavor of Malay. They also spent several centuries as a Portuguese colony, and developed a unique culture different from the rest of Indonesia.
Look under the hood of most of the Christian/Islamic conflicts in sub-Saharan Africa, and you will see ethnic and/or cultural (eg: farming vs. herding) differences as well.
Religion is just part of a society's cultural package, so it is inevitable that when cultures clash, religion will come into it.