I agree that opinions are not all "equal" - heck, even my own opinions, as some are informed, and others are just a general view which I recognize is not well informed, and would never state as a "belief" just my initial view/opinion.
But, as OP is specifically asking about how to address others in a social setting, when they offer a strongly held opinion which seems unsound, I would not use or recommend the phrasing of OP's response - which contains a likely equally inaccurate statement. There are multitudes of "scientific" studies on almost any subject/opinion, and whether or not "any" such study is "reliable" is also a matter of opinion.
When confronted with anyone asserting an opinion which I consider invalid, or poorly considered, I will generally listen politely to a statement, then reply there are a range of views on the subject and/or offer bean dip - unless it becomes a monologue or attempt to convert the listener, then I may either more forcefully beandip, or suggest that respect for others opinions is the currency polite society requires in return for listening to anyone who wants to share their own opinions.