Yes, of course, without God everything becomes subjective. Morality becomes relative. But I’m hesitant to just say “homosexuality is wrong because my religion tells me”, because I’ve basically done that in front of like 20 people, and one replied “Which is why we need to get rid of religion”. I said “You mean get rid of me, right”? He replied “Well, no”, and I said “But you’d have to, because I’m not going to give up my religion willingly”. That gave him pause, but the point is I don’t like letting people think that without religion, problems just go away. But maybe I shouldn’t care what they think.
I have two points to make:
1)Regardless of whether or not your argument is ultimately religiously based, the "scientific" narrative of origins deviates from that of the Torah. Torah trumps "science" . . . always.
2)You need to get the idea that there is a separate category of life called "religion" out of your head. There is only G-d, and G-d's commandments apply to every aspect of life . . . "religious" or not. Furthermore, the only reason anything is objectively wrong is because of Divine decrees. There is no such thing as secular morality, secular ethics, or (ultimately) secular laws. There is only G-d. Unfortunately, conservatism is poisoned by the "western civilization" of Greco-Roman philosophy, which is precisely why this has been building for the past two thousand years. Plus conservatives make use of this identical "enlightenment" ideology in condemning islam.