I don’t like this dude. And he might have gotten the tattoo just to provoke people. But the concept of کافر (infidel) is real in Islam, and the religion clearly distinguishes between Muslims and non-Muslims. I can see why a non-Muslim might take issue with that.

https://www.theguardian.com/us-news/2025/mar/27/pete-hegseth-tattoo-arabic-language