Why do a lot of religious people refuse to admit there’s violence in their scriptures?

One of my friends is a Muslim girl from Hungary she’s very moderate and dresses like typical western young adult woman she doesn’t wear head scarfs are anything like that. We don’t talk about religion much but one time I did try to make the argument to her in a way I hoped she might understand. I said something like “you might be very moderate but isn’t it possible that a religion that follows a prophet that was known to get into wars courage encourage people who are not civilized as you to commit violence in the religions name?” She told me that there was nothing in Islamic text that endorses violence and then she asked to change the subject because she didn’t like arguing with me. I didn’t keep arguing with her about it after that so I didn’t tell her this but her claim that there’s no violence in Islamic text is simply not true. However it’s not just Muslims who deny this. Many religious people of all faiths deny this. I seen a lot of Christians accepting of homosexuality deny that the biblical texts that endorse murder of homosexuals exist. Islamic terrorists don’t just do what they do out of their own free will. Islamic scripture clearly says to behead non-believers, hang homosexuals, etc. Groups like ISIS is just taking what the scriptures say literally. Of course sane people who are not complete barbarians don’t follow any of these scriptures that are largely in the Old Testament today but they are there and what good is pretending they don’t exist?