Apparently the Ancient Romans used to say "Qui tacet consentire videtur, ubi loqui debuit ac potuit", which more or less means silence looks like consent, so you should speak up when you have the chance.
When you're sitting in church listening to someone spout anti-science trash, racist spew, sexist bullshit, or any other nonsense that no one deserves to be subjected to, think about how your silence might be perceived as agreement. When you have a roomful of people who let shit slide it feels very much like a room full of coprophiliacs united heart and soul. Be aware that feeling like everyone but you is into it might contribute some pressure for you to conform. Don't stand for it.
Differences are okay. I think. At least I want them to be. Speak your mind. Let's see what happens.