There is no evidence for this belief.
It's not a belief.
It's a self evident fact.
When it comes to determine how accurate a certain belief is, one has to necessarily verify its accuracy with respect to observable reality. Since "accurate" in this case means how well it reflects reality.
The data that shows how well a claim reflects reality, which can come in many different forms, is called "evidence".
So when there is no evidence, when there is no way to verify a claim against observable reality, then right of the bat - pretty much by definition of these words - believing said claim (which means: to accept as accurate), can not be reasonable / good.
How do you conclude which belief is better (in reflecting actual reality), if not by comparing and evaluating the supporting evidence? And how do you do that, if there is no evidence?
Ideologies, including the secular humanistic 'Rationalist' ones are simply fictions designed to support subject value preferences taken as being axiomatically true.
False equivocation.
We're talking about religions. The belief that (supernatural) entities and / or forces exist. These are beliefs about reality, how it works, what actually exists and doesn't exist... Whereas secular humanism are worldviews concerning on how best to organize society and to provide a moral framework.
Humanists tend to favour some form of consequentialist/utilitarian ethics anyway, in which case why should 'relative truth value' even really matter?
It seems like an irrational point of principle akin to a religious tenet in this context.
Again, humanism has no part in this.
