Can I eat In N Out burgers? My shia friends eat it and when asked they say that Allah says in Quran that you can eat from the people of the book and this is a wholesome christian establishment. Therefore it’s halal.

According to Shia Islamic law you can only eat meat that which has been slaughtered according to Islamic guidelines. Just saying name of Allah on it does not make it halal at all, and consuming it would then be haram