Practically nothing can be considered an 'objective opinion'.
Well duh. That's quite literally an oxymoron.
Believing in objective morality doesn't mean being certain that your opinion on what is right and wrong perfectly corresponds to what is objectively right and wrong.
So do you believe in a knowable right and wrong? My own personal opinion is that such a thing probably does exist, but has been imperfectly revealed to humanity, meaning that, obviously, we all have our own reflections on what is moral and what isn't. However, if you believe in a knowable right and wrong surely you would ensure that your moral beliefs correspond exactly to that objective stance (not a gotcha, just curious).