Don't feel too attacked. Read it again, when youre calm(er) in some minutes...
Keep in mind that many many grew up more atheist, than christian. Keep in mind that the (big) churches are rather taking part in the deception, than fighting it.
You claim that you "know this board" but do you really or only assume you'd know? Since even wrong knowledge feels much more comfortable, than not knowing... right?!
Try to be a rolemodel to them, try to understand why they are "this way" and probably start with your very own language and expression, first.
I suggest you to check out (audiobooks) about communication theory, how to argue/talk with people and such things. preferably from pre 1950''s (or based on [original] books that are pre 1950's).
Dale Carnegie is very recommended.
If you have faith, there will automaticallsy come other changes with it. Such as a change in language and behaviour and reasoning. Maybe some sort of calmth, too.
Faith does WORK. Work is a change. If you work as a carpenter, you're going to change some planks and wooden pieces, into a table or desk. That process is, what you call work. The change from one state, loose woodparts and boards, to another. A fully assembled table or desk. (or bed, couch, cupboard; whatever you can imagine).
So FAITH ALONE does it's work...
Some of the turth is, that "christianity" is the best, that is humanly possible. For humans are full of flaws and will never get rid of that. And humans are also influenced by evil spirits under the heaven.
There is more truth in Jesus Christ, than "only" being beneficial for society.
youtube.com/watch?v=h1DcWw9geig