Alceste
Vagabond
I think it's as simple as he thinks it must be a belief if you use the word belief in a sentence. What I don't know, is if it's a matter of an inability to understand logical concepts, or knowingly making an irrational argument out of misguided stubborness. Either way, it seems to be a lost cause.
I think it is probably out of having a niggling, persistent conviction you are dying to express but no talent for the use of language.