> what op means by belief system
Not sure whether I'm too abstract or not; a belief system to me is a set of assumptions on what seems right or reasonable, which is, ideally, as sound as possible with what we already know. Some of these assumptions are fuzzier, and some are more precise, principled, and, for somebody, possibly even dogmatic.
> we have a suffixed "ism" it gets dogmatic
It may usually become dogmatic, yes. To me personally -isms are paradigms, which may be adequate depending on context. I'm mostly comfortable with rationalism in particular as something relatively universal, yet I think even it can be somehow abused/misused depending on context.