The reason why living beings in the celestial realm were regarded as gods by the common people was that after stepping into that realm, their physical bodies and true spirits would undergo some kind of mysterious transformation. They would be in harmony with the great Dao of heaven and earth, and could shine with the sun and the moon, immortal and indestructible.
Even if the heavens fell and the earth cracked, or the sun and moon overturned, they would not fall. They would remain in the long river of time and were invincible in the world.
Of course, being immortal didn't mean that they couldn't die. The power in the world was endless. If they encountered a power that they couldn't withstand, they would also fall and become a spray in the long river of time, disappearing from the world.
In comparison, the creatures in the immortal Dao domain were only harder to kill than ordinary cultivators.