This seems like an unproductive exchange where nobody's mind was changed. Insults can be very gratifying when there are people we're frustrated with but they don't disappear when disrespected. They continue to exist, maybe more quietly, but they dig in their heels further and become more determined to never believe any different, to convert others and to have children largely for that purpse, so that people like them will always outnumber people like us. Thus the problem not only persists but expands.
A more constructive exchange might have started with:
"Suppose for a minute there's a group traveling about your area, led by a charismatic speaker who claims the world is ending soon. He promises he alone can save you, but only if you sell your belongings, devote the rest of your life to him, and cut off family members who try to stop you.
He may also want to change your name, assign you a new identity, advises you to leave your home/job if necessary to follow him, and says that if you don’t love him more than your own family then you’re not worthy of him. His followers wrote a book about him in which he performs many miraculous feats, but no contemporaneous outside source corroborates their claims. What sort of group is that?"
...followed by all of the usual defenses and followup arguments illustrating what they are in. If you get efficient at this you can have them deconstructed in under an hour. They will never change their mind on the spot because they went into the exchange with the explicit goal not to give you that satisfaction no matter what, but you can plant a seed that will sprout in your absence as they explore the implications of what you've told them on their own time and terms they're comfortable with