The reason I ask is because I’ve heard this reasoning many times from gay friendly churches.
I'd say that male homosex is a capital offense, Genesis 19 or no Genesis 19.
Also the gays would argue that Leviticus was not even written yet during the time of Sodom and Gomorrah...
For that matter, neither was Genesis. (That's not actually true. The Torah was written before the universe was created.)
I don't understand the problem you're having. Homosexual relations are forbidden. Why do so many people think the whole issue hangs on Genesis 19?
It’s not MY problem, it’s the problem of many supporters of gay marriage and gay relationships ( yes, it includes those who attend synagogues and churches ).
The want to nuance (or “equalize”) things by insisting that the prohibition against homosexual sex is SIMILAR to the prohibition against heterosexual sex.
And since the instance mentioned in the Genesis passage talks about the men of Sodom wanting to gang rape the strangers, this does not apply to gays today because they don’t want to rape anyone.
Therefore, if you allow gays to marry, the prohibition is gone.
[not my argument, just telling you what I’ve been encountering when I talk to some people ]