It seems a silly question to ask, given the self-evident answer: we know that all beliefs and opinions are not equally valid. Obviously, it's important to acknowledge that the person who believe something believes it to be true, but it doesn't mean it is.
The reason I raise this question is that most of us in the skeptical community patently reject the assumption that all "truths" are equally valid. What matters is evidence. Where there is no clear answer, rather than assuming a position of absolutism regarding "truth," we tend to adopt a "wait and see" approach or an honest "I don't know" approach.
This is not the case in most areas. Truthiness is often more important than truth.
Chantal Sicile-Kira has a Thanksgiving post up at Huffington Post that troubles me. The part, I suppose, that bothers me most is this idea of truths, as if everyone's version of reality is equally valid and true. She writes, "The autism community has it's differing opinions, because all of our perceptions and experiences are a part of the mystery that is autism: we share a similar label but our personal stories, perceptions, beliefs, and truths are different. And this needs to be respected" (punctuation intact). Had she left it at perception and beliefs being different and needing to be respected, I believe I could endorse that. In order to communicate with others on similar journeys but with radically differing perceptions, we'll have to respect that those perceptions are different or no communication can occur.