"I’m entitled to my own opinion"
Yes. Yes you are. This translates into you having the right to formulate, state and defend your opinion. It also means you should not be censored so long as you are not doing it in a non-destructive manner. However, it does not mean that you’re allowed to be pig-headed and believe that your opinion is scared and should not be subject to question or criticism.
"I’m not trying to be sexist/racist/ homophobic/ableist/-ist but…"
If you need to start your statement with that, then you probably are sexist/racist/homophobic etc. I’m sorry to be the bearer of bad news.
"No offense but…"
If you have something to say, say it. Saying "no offense" does not absolve the speaker or otherwise make the offensive statement non-offensive. It will be considered offensive and the person will be offended, but at least you’re not being a coward and trying to sugar coat it.
"That’s so gay"
That’s so Asian. That’s so fat. That’s so Catholic. That’s so heterosexual. I’m sorry, how does that make any sense?