You're free to believe what you want, and if what you believe keeps you alive by preventing you from up-ending established tradition, that's a good thing.
However, if your belief that all humans descend from Adam leads you to thinking that importing little boats full of random un-vetted Africans is a great and good thing because We're All Brothers and helping your brother is an obligation, well, if you end up living in an African style shithole as a result, then that belief a bad thing.
Trying to explain that belief systems have real world consequences is kind of the breakfast question for a lot of Christians, because they just say "it's not belief, it's fact", but those who can't step out of their belief system long enough to see if it's suicidal will be replaced by those who can... ¯\_(ツ)_/¯
