Sometimes you gotta connect with someone on a personal and cultural level before they'll listen to you. People believe what their group believes, because 1) it helps them fit in, and 2) they trust the collective wisdom and values of their group more than they trust their own limited personal judgment and life experience. If you threaten the beliefs that help them get along with their peers, they're gonna shut down to protect themselves before you even get to the logical part of their brain. The best way to get past this is to connect with them first over shared values and life experiences, because it kinda legitimizes what you're saying and gives them permission to think about it.
Just my 2 cents, not aimed at OP or anyone in particular