This is a very strange idea.
If I say "Night follows day," is that true only for me? It happens whether I believe in it or not.
Or suppose I say, “If you believe in death, it’s true for you.” Please—death will come for you whether you believe in it or not.
The Bhagavad-gita says, “For one who is born, death is certain. And one who dies is sure to be born again.”
According to the Bhagavad-gita, this is a law of nature. You can decide for yourself whether to believe there’s such a law or not. But laws of nature—whatever they are—do not not depend on one’s belief.