For us humans, the concept of good and evil surely exists, otherwise we couldn’t have laws. I don’t believe it exists after death.
I believe in life after death. And although my reasons for hoping for eternity in Heaven are complex; you can boil it down to a simple concept:
Live a Godly and pure life and go to Heaven. But then if you die and there is no Heaven... You still lived a good life.
Live a sinful and evil life and go to Hell after you die. For eternity. But - if there is no life after death - you get (as it were) a get out of jail feee card, and you don’t go to Hell.
But you still lived a sinful and evil life. And every person who ever lived knows the here and now benefits of living a good life is far better than living a miserable life.
Live for God. What have you got to lose?