... if you are not a Christian, or don't believe the Bible, why is it important to you to try to make it sound like God and/or the Bible is /does not condemn homosexuality?
If you don't believe, it should be irrelevant to you.
Probably because people claiming such things are using their own personal interpretation. And just as the BIble can be used to defend things like child abuse, slavery, and segregation, it can be used to condemn homosexuals too. But only from a certain point of view and interpretation.
Lev 18:22 for instance doesn't "condemn" homosexuality. It calls gay male sex acts 'abomination.' But in the context of verses before and after condemning an extant religion at the time. It's not condemning the sexual orientation but specific acts the ancient Jews observed being done by their contemporaries. Judaism forbids the practicing of any non-Jewish reliigon or religious pratices (Christianity, this means you too.) So they specificly forbade many things those religions were doing at the time from shaving their beards, tattoos, religious prostiution, and male homosexual sex acts.
Pointing this out to those who rip things out of context and try using it to defend their personal bigotry is no more a thing than would be someone knowing the contents of a Harry Potter novel and argueing against those trying to say Harry and Ron were in a gay relationship.