Technically I do consider religious views when talking about homosexuality and gay rights - I consider homophobia to be disgusting and stupid whether it comes from religion or not, and not something that is worthy of any respect.
There are people who genuinely think homosexuality is "unnatural", a "perversion", gay couples shouldn't be able to adopt, and who compare homosexuality to paedophilia and bestiality. Those people are homophobic, which is different to those concerned about the "definition of marriage" (even if I myself disagree with them).
The right for gays to be protected from discrimination and have equal rights overrules the "right" of homophobes to discriminate. And let's not be in any doubt, some people would love it if discrimination against gays became a thing again.
Those people are entitled to hold and express those views, but they can't cry about it when their views get criticised, and when they lose a debate or referendum.