Non-Christians

Why do Non-Christians try to tell Christians what we do or don't beleive in. I am not talking about ex-christians; the ones who may have fallen away from the faith. But the ones who never stepped foot in a church or opened a bible.

Them: "Christians believe in a reincarnated 6 headed penguin that drinks blood."

Me: " oh wow, I had no idea i believed that. Thank you for letting me know." 🙄