My job largely consists of listening to a lot of people's opinions, sifting through them, and making a hopefully balanced decision. As such I'm pretty tolerant of people voicing their opinions, personally I have as strong opinions as anyone - and then some. In general conversation though I think the big challenge is not if you voice your opinion, but whether you do so acknowledging that someone else may have a different opinion that they truly believe is equally right and important. There's a huge difference between "I believe X is the best way of doing something " and "X is clearly the only way of doing something".

However there are a few topics I really don't feel are up for debate in the first place. If the scientific consensus is overwhelming on a certain topic, sure you can still discuss it, but I don't really see the point, unless you happen to be an expert on the subject.