Xians (Christians said our way) may be more than annoying.
They will never take a no as answer, they will always try to convert you or "bring you back" even behind the scenes; their behavior is compulsive as xianity is a program built to self-replicate on other people through forced faith. Centuries ago, people were burned and killed for not complaining to xianity. Today this is not possible, but their mind works in the same way, unconsciously.
As your xians are active preachers, I'd say using bruteforce attack on them like repeatedly refusing their faith will not work, as they will not listen to any of your explainations.
Being smart and leading them to think you are not worshipping the Devil anymore (Satan is God in truth), will be much more helpful. Satan understands if you don't declare your faith in public - it's only a matter of survival.
If you live with a heavy xian family and you are able to, I'd consider moving out because living under their negative energies and influence is no good. If you cannot, you will need to build a space all for you that you will protect with Satanic energies (secretly) and keep energetically clean, so you have a safe zone.
Xians are like virus, they attack your operative system (mind) behind the scenes and try to block your programs (meditations).
They would even force you to psychiatric drugs, hospitalization, and other coercive ways of "healing" you.
Stay on the safe side, work secretly to find your way to Satan, as it seems your mind is willing to drive you here.