In the early phase of Buddhism, still represented in the Hinayana school of Ceylon, Burma and Thailand, there is no place for God. God does not come in any of the Four Noble Truths, neither in the causation of suffering nor in the path of winning nirvana. Lord Buddha remained silent about God. For him it was useless to speculate about God. Any venture in this direction was called a metaphysical heresy. From this silence of Lord Buddha, it has been inferred that the Buddha did not deny the existence of God. But in the long history of Buddhism, the Buddhist have tried to refute every proof in favour of the existence of God. Hence, Buddhism may be regarded as an atheistic system of religious thought.
If there is any entity, which may be called supernatural, then it is nirvana. Many thinkers regard nirvana as a positive entity, corresponding to the nirguna Brahma or even Brahma of the Upanishads. In the Milinda Panha, Sage Nagasena thus describes Nirvana to King Milinda.
0 King, Nirvana is not born, neither does it grow old, it dies not, it passes not away, it has no rebirth.`
Nirvana is neither past, nor future, or present, neither produced nor can be produced.
One can easily compare the passages quoted here with the one passage in Kathopanishad:
The wise one (Brahman) is not born nor dies.
This one has not come from anywhere, has not become anyone.
Unborn, constant, eternal, primeval, this one is not slain when the body is slain".
But this is too slender a thread to support theism.
True, at one time Lord Buddha was credited with omniscience. But Lord Buddha has so defined it that from this omniscience one cannot conclude his Divinity. Lord Buddha claimed Omniscience in a very limited sense i.e.,
He remembered his past lives,
He could see beings born into new births, according to their Karmas i.e., the law of trasmigration.
He got release and had knowledge of this i.e., the path leading to the cessation of suffering.