Do Jains believe in God, creator or supreme being?

Short answer: No. Jainism does not posit a creator God or a universal, all-powerful maker of the cosmos.

• The universe is eternal and operates according to its own natural laws (dravya, samyak karma, etc.), with souls (jivas) moving through cycles of birth and rebirth.
• There are gods (devas) in Jain cosmology, but they are not creators of the world. They are also finite souls who enjoy heavenly realms for a time, and they too are subject to karma.
• The ultimate spiritual aim is kevala jnana (omniscience) and moksha (liberation) from the cycle of birth and death, attained by an awakened soul (tirthankara or Arihanta) and then by the liberated soul (siddha).

There are slight differences between Digambar and Shwetambar interpretations regarding a supreme being:

• Digambaras typically do not regard any god as the creator or ruler of the universe; Ishvara (if referenced) is seen more as a perfected soul who does not create or govern the cosmos.
• Śvetāmbaras sometimes speak of a supreme, perfectly enlightened being (Ishvara) who governs the material universe, but still not as a creator in the way monotheistic traditions conceive of God. Even in this view, Ishvara is not the originator of all things; the cosmos and karmic order precede and outlast any such being.

If you’d like, I can provide exact Jain scriptural terms or brief quotations to illustrate these points from the Śvetāmbara and Digambara traditions.