RTRs only harm kike souls. They have no detrimental effects on Gentiles. Only positive ones, such as separating them from the jooish crap.
ISA is good for single-rune bindings. If you want to use two runes, you can add Gebo.
As for the affirmation, the best one is found on JoS: https://www.joyofsatan.org/www.angelfire.com/empire/serpentis666/Binding_Spell.html
I say best ones because it's more complete than other suggestions I heard in this forum.
Other advice on sealing your aura against them and other very good advice has been given.
If it was me, I'd do a one-time binding and a more long-term de-xturdanisation spell, the second only if you really care about that person.
EasternFireLion666 said:
Another thing you might try, but this in case you don't want to cut ties but just make them see xianity is a scam, is to try a ritual, but adapt it to that person. Stormblood gave me this idea recently in case you wish to do this.
https://www.satanslibrary.org/Rtrs/RabbiChrist.html
Use perhaps the 1st and 4th affirmations from this one and add a new one like "The christian thoughtform is dead and void from the soul of X". Or maybe just this affirmation.
His idea is very good in my opinion in case you want to cool him down a bit
How did that go for you, btw? Could answer it in your post, so I don't hijack this topic?