The fact is, people from all backgrounds and political viewpoints hold opinions which they view as absolute. Whether that's "being anti-gay is equivalent to being pro-slavery" or "abortion is murder", people are going to disagree even if they are both guided by the same fundamentally good goals.
All is not as it seems when you change the optics (edited, restored).
PS I liked the line about optics better.
Gay people: We'd like to get married.
Government: Okay, here you go.
It's only because assholes go crazy about it that it's a problem.
Also, gay couples have been doing the "set up a bundle of contracts" thing for years. It's expensive and doesn't actually provide the same protections that marriage provides.
Some people justify their intervention in all these issues by claiming that the up-coming generations are everyone‘s future, and needs to be protected as such. Hence many laws to prevent them from harm, most of which I’m sure you adhere to.
The salient cases are often about disagreement about which is the greater harm: being Métis in a race-based, or living in a race-based society? Some (abortion) are about disagreements on what constitutes a child.
I don’t think that you, or rather some other people on the same side as you on such issues, choose to make themselves better persons by disparaging your opponents openly. Like you, they are worried, and inconsistent. And, if you step away from absolutes, they would agree with you on many actual cases. Cognitive dissonance (which, admittedly, happens more often among your opponents) is very painful, and you want to respect that to effectively make the world a better place.