You seem to be making a bunch of unwarranted assumptions about me. What gives you the idea that I'm not aware that if I had been raised in a different social context I'd have different opinions? I don't think I'm right because these happen to be the opinions I've always had, I've actually put thought into them over time and they've changed as I've acquired knowledge. And I could still be wrong, of course, since I surely don't know everything.
I used "colonialism" because it's a specific ridiculous claim I've seen regarding FGM. Specific, because "colonialism" has a specific meaning: that of one country colonizing, exerting political control over, and exploiting another place. So Britain conquering India (as well as a large number of other places), and European countries exploiting Africa are certainly colonialism. Probably Roman expansion would be colonialism too, though that's not what most people are referring to when they use the word. But I don't really see how the rest of your examples can be classed as "colonialism". Imperialism, maybe (except for freeing the slaves, which just seems kind of like you through it in randomly), but that's a different thing. Colonialism was bad because the specific thing that that word describes is bad, not because "colonialism" means "bad stuff". Anti-FGM is certainly Western, but not everything that is Western is colonialism, or imperialism, or bad. I'm sure some people who oppose FGM have imperialist attitudes about it, it's kind of inevitable really, but there are plenty of arguments against it that aren't imperialist.
As far as gay cake goes, I understand why these bakers feel the way they do. I do. I just think they're wrong. It's unreasonable to expect that you'll be able to convince everyone else of your opinion, so in the absence of that, it is best to do your best and make laws to stop the problem.
It's (broadly) [faɪ.ˈjuw.lɛ]
Quis vult in terra stare,
Cum possit volitare?