RaggyCat- My .02 is if there's something in your mss that you know is an absolute no for some people it should be front and center, so they know what they're getting into. Others may, ok will, disagree. The mss I'm currently querying features an unlikeable protagonist who abandons her husband and children (because she wants to, nothing dramatically horrible in the home. I have it in the query and the opening pages. Will a number of agents auto reject because of it? Yes, but because it's pivotal to this character and her story, I want it right there. I don't think someone who would be completely turned off by this magically won't be if I wait until the twenty-first page, if that makes any sense.
This is pretty much how I live my life. Full disclosure avoids ugly bait-and-switch or awkward post-jection instead of pre-jection. In the case of my query, I reference a religious figure in it. Classic SF never shied away from incorporating/reenvisioning religions, but so much contemporary sci fi operates in a Roddenberry-esque secular fantasy world. It makes me think agents have reacted to the atomization of publishing (niche religious market publishers, for instance) by avoiding ALL treatments of religion in general market books and not just the pious ones that could also be published by niche companies. I don't see how I could described the changes of human identity, family roles, and psychological self-awareness in my future world without incorporating religious elements.