My philosophy is if they are truly happy with what they believe and aren’t harming other people with vitriolic speech or dogmatic beliefs just leave them be. It’s not harming anything for them to comfortable in their little bubble.
But when they put on their “holier than thou … I know better and I am going to push my beliefs on you” hat the gloves are off. Although it’s unlikely you’ll change their mind, you can usually score a few jabs that rock their world just a smidgeon.