The bolded part is a direct opposite to the life-long search for truth you advocated in the sentence before it so i must ask, are you serious?The problem is belief.
It's not that belief is inherently bad. We humans, while able to assess evidence, are particularly ready to hold beliefs against evidence. This has made us stronger. Has helped us constitute social groups larger than the family or the clan, has helped us harvest natural resources on a scale that no other species ever did on our planet, including the rest of the species of the Homo genus.
We get fond of our beliefs, so fond that we attribute them qualities they don't have: rational, realistic, scientific, beneficial for the common good or for the self...
But our ease to latch onto beliefs makes it hard to be critical with them. We are very good at criticizing those beliefs we didn't adopt, but very bad at criticizing the beliefs we like, just as we are bad at criticizing the people we like opposed to the people we don't.
All of us are reasonably intelligent. The problem is that we use our intelligence to defend our beliefs, instead of to assess their truth. And hence we get extremely intelligent people defending extremely stupid beliefs. And thinking themselves the only thinking persons.*
Can we get rid of this? Well, i think it's very difficult. Our love for our beliefs is entrenched in our genes, so until that's gone... Meanwhile we need to put our best effort to be more critical with our own beliefs than we are with the beliefs of others. To use our intelligence to help us find the weak points of our mindset, and attack those points. But how to do this without adopting new beliefs to substitute the old, ending up with the same problem again?
*And yes, this is a big warning sign! The more alienated you feel from the rest of the people, the more you should worry that maybe your beliefs are wrong, and you should reexamine them immediately.