Buddha said that there are thirty one planes of existence. A being is born in one of these thirty one planes according to good and bad karma. ALL thirty one planes of existence are subject to the Law of Impermanance.
1. There are 4 States of Unhappy Realms – Dughathi
[Niraya (hell), Animal Kingdom, Prethas or ghostly beings, Asura demons]
2. There are 7 Happy States – Sugathi
[Realm of human beings (a mix of happy and unhappy experiences), SIX KINDS OF DEVALOKA OR HEAVENLY REALMS (happy and pleasurable experiences)]
[The devaloka are of much higher sugathi standing than the human realm!]
3. 16 kinds of Rupaloka (realms of fine material form)
4. 4 kinds of Arupaloka (formless realms)
So, there is no omnipotent god as taught in Christianity, Islam and other religions that believe in a Creator, all-powerful-higher-being.
When a being is born in one of the devalokas as a deva (god**) as a result of extreme good karma, it is not permanent. Although the timeline in devalokas is unfathomably long in earthly years, the existence as a deva will come to an end for all devas (law of impermanance). Once that good karma is exhausted, then the devas will be born in another, suitable realm / plane. Taking the extreme example of say a human being who has a lot of really good and really bad karma, that person may be born as a deva and once all the good karma is exhausted may be born in a Dugathi unhappy realm as a result of the extreme bad karma accumulated in his / her human existence.
The only way for any being (including devas) in any of these 31 planes of existence to cease existing is to attain nirvana.
Note that being in Niraya (hell) is also temporary. Once the bad karma ends the existence in niraya will end and the being will be reborn in another realm. It is quite like we observe the beings in the human and animal realms being born and dying.
** Personally I prefer not to use the word “god” in conversations, instead I use the term deva, because in my experience once the word god is used it becomes that much more difficult to distinguish between the Creator-of-all-things, all-powerful God and devas in the six heavenly realms. I guess because most other major religions use the term god in that (Creator) sense, it is like the acceptable meaning to the word god.
In time, deva might also become a word as readily recognised in the English language as kamma…
In case you’ve been wodering why we transfer merit to devas after each dana, bana etc, I believe it is because beings in deva existence are unable to accumulate merit for themselves.