Answer:
It is a pagan belief and contrary to everything God says. God says…Hebrews 9:27 And as it is appointed unto men once to die, but after this the judgment:
Reincarnation is a convenient belief to allow someone to continue to return to this earth, so that even if someone rejects Christ they will have other lifetimes beyond this one. The fact of the matter is hell is full of people who believed they would be reincarnated and rejected Christ’s promise and gift of eternal life.
It is probably going to take l lot of prayer on your part and persistence in doing good and loving these people because this is a very strong spiritual stronghold they are under. I too know people who believe this way and they are very, very stubborn in their beliefs. I pray they will come to humble themselves while there is yet time.