I Heard You Want to Become an Immortal

The protagonist adheres to the teachings, does good deeds throughout his life, and accumulates blessings. Unexpectedly, he still died under the catastrophe. Fortunately, he saved a little bit of his soul and was reborn as a demon, but unexpectedly discovered a cruel truth. From then on, the road to counterattack began. I heard that you also want to become an immortal?