Each time that I have broken my abstinence and then came back, I felt as though I needed a degree of faith that I could recover by doing what I was doing. For example, when I was worried about being able to make it to the next day without drinking, it was not the time for me to be questioning if going to AA meetings is an appropriate long term plan.
So, I did little things to keep myself on track and keep myself thinking that I am going to recover by moving forward.
I think posters here are calling that "belief" and saying that it was important for them to not get overwhelmed with thoughts of failure, by believing they can recover.
After I got stronger in my abstinence, I no longer needed to fear thoughts of failure and the notion of fostering faith in my recovery was too obviously false and I didn't need the hand holding any more. I could then reason about aspects of my recovery process without fearing that if I do that I will fall into despair and start drinking again.
In other areas of my recovery I did and still do have fears of failure that I try to address by adopting a degree of faith that I can overcome the failure. But, I know it's a way of tricking myself.
I don't think the original post is using "belief" to mean "faith" or "think". It's not saying that it's dangerous to think that it's possible to recover, or it's dangerous to have a degree of faith that you can recover.
If I were to stay in the mode I was in in desperate fear of failure and didn't recognize the temporary cheering up aspect of that faith. If I held it as a truth that is not suspect:
"the door on rational discussion and scientific enquiry" would be " kept closed by these ideas, and ultimately harmful to the process of coming up with New and better ways of understanding addiction and reducing harm in the general population."
I think the post is using "belief" to mean that and in that sense I agree with the post.
I see that happening in recovery circles. So, the topic is important, I think.
What I don't see in the post is that I don't think you can simply decide not to have beliefs in the sense of the post. Supposed truths that we hold as beyond suspicion are not something we can simply decide not to have. If they were, we would not be holding them as beyond suspicion.
We can decide to adopt a degree of faith about a process, though. As long as it is recognized as intentionally postponing reasoning about something, it doesn't contradict the idea that unquestioned truths that we hold are not good.