There are many points in the book I'd like to discuss, but haven't had time to do so. However, there is one I can briefly summarize, that I think touches upon why many exmormons get frustrated with believers who know the controversial facts but continue to believe.
Religion is a team sport. It's all about building a community, a tribe of people devoted to one another, willing to sacrifice for one another, and imbued with a system to discourage free-riders. It's not a perfect system, but it has been a system that has enabled the members of the team to thrive in a way that isolated human beings could not.
Doctrine is simply team colors. It's a way to mark the members of the team. The specific colors (doctrine) aren't what really matters. What matters is that you're wearing the right colors, that mark you as a member of your team.
People who leave the church, for some reason, are able to consider the possibility of life outside the team. I think there are many reasons for the ability to make such a consideration, which is too threatening for others to even consider. Once they consider the possibility of life outside the team, they are willing to look critically at the colors (doctrine), and reject the team on the basis of the illogical and unsupportable claims of the team (religion). And all religions make illogical and unsupportable claims. It's what makes the arbitrary quality of the demands and rules acceptable. Faith. But those who are still on the team, and cannot deal with the aspect of life outside the team, simply cannot look critically at the colors.
As Haidt says, morality binds and blinds. Whatever the moral code is, it binds people together. It also blinds them to the often arbitrary nature of their sacred values.
Morality binds and blinds. This is not just something that happens to people on the other side. We all get sucked into tribal moral communities. We circle around sacred values and then share post hoc arguments about why we are so right and they are so wrong. We think the other side is blind to truth, reason, science, and common sense, but in fact everyone goes blind when talking about their sacred objects. (page 311)
Why doesn’t sacrifice strengthen secular communes? Sosis argues that rituals, laws, and other constraints work best when they are sacralized. He quotes the anthropologist Roy Rappaport: “To invest social conventions with sanctity is to hide their arbitrariness in a cloak of seeming necessity.” But when secular organizations demand sacrifice, every member has the right to ask for a cost-benefit analysis, and many refuse to do things that don’t make logical sense. In other words, the very ritual practices that the New Atheists dismiss as costly, inefficient, and irrational turn out to be a solution to one of the hardest problems humans face: cooperation without kinship. Irrational beliefs can sometimes help the group function more rationally, particularly when those beliefs rest upon the Sanctity foundation. Sacredness binds people together, and then blinds them to the arbitrariness of the practice. (page 257)
This is why we can have the same arguments, debates, discussions, with believers until the cows come home, and if the believer isn't able, for whatever reason, to consider life outside the team and thereby to actually question the chosen colors, it won't make one bit of difference in the end.