The very best cultures are the ones that say, “Go explore other cultures.”
If you feel like you have to defend your culture with gatekeeping (in either direction), ostracizing the outgroup, condemning heretics, or any other sort of purity controls, then your culture probably isn’t very good.
The best cultures want cultural exchange. They’re strong enough to take the best and leave the worst, to grow through that exchange, and to welcome new members all the time. Whether you’re a world-wide religion or a fan club for a TV show at your high school, you should always be willing to encourage your members – including yourself! – to go out and experience the vast other. And you should invite the other into your space to experience yours.
That’s the best gift of all.