Lots of things are sins, and you can’t legislate against all of them. Homosexuality is a grave sin, and with things like it along with murder and abortion, you can and should legislate against them.
Or if you want to take out the word “sin”, we could say that it violates a basic principle that has held society together throughout its history—marriage.
From that standpoint, it needs to be banned. As for why we shouldn’t ban everything that goes against Christianity or the Ten Commandments, see post 115. But homosexuality should be banned not only because it goes against them, but because it is dangerous to society.
Who gets to decide what’s a “little” sin, and legislation subject to constituional constraints, and which ones are the “big” sins that get a pass?