I'm my limited understanding, agnosticism
is the belief or opinion that the existence of God cannot be known, or cannot be proved or disproved. Thus, the agnostic would say that the only true statement one can make about God's existence is "I don't know". This agnosticism could also be applied to other supernatural claims, such as the belief in a soul or in an afterlife. An agnostic would say that since there is no convincing evidence one way or the other, we cannot really say whether or not such things exist or do not exist. This is similar to atheism, but the two are not exactly the same. An agnostic may say something like "I don't really see any evidence for God, but I can't be sure, so I really don't know", whereas an atheist (depending on the "strength" of their atheism) would probably say something like "The lack of evidence for the existence of God leads me to believe such a being does not exist".
So is Buddhism agnostic? Again, I've only been on the Buddhist path for about a year, but in my understanding Buddhism (at least my own interpretation of Buddhism) is not agnostic. The Buddha addressed the idea of a Creator God and quite vocally rejected it as being false on several fronts. He argued that 1.) If a Creator God existed, then nobody could be held accountable for their actions, because ultimately if we are all creations of an all-powerful God. Therefore, such a God would bear final responsibility for the existence of both good and evil people, 2.) If the universe were truly created by a God, then who or what created God? This was in response to those who asserted that God must exist, because everything needs a cause, and since the universe didn't cause itself, it must have been created by God. The Buddha pointed out the flaw in this assertion by then further asking the obvious question - since everything needs a cause, then what caused God? My understanding is that Theravada Buddhism has always considered the God-idea to be a form of wrong view.
However, where all of this gets tricky is that while the Buddha rejected the idea of a Creator God, he didn't reject the existence of the devas
, or "gods". In fact, one of the titles of the Buddha is "Teacher of celestials and men", and the Buddha is said to have taught Dhamma to human as well as heavenly beings. My understanding is that these devas, although more powerful and long-lived than humans, are of no importance in Buddhist practice. They are bound by kamma
and trapped in samsara as we are. Since virtually nobody (without some kind of supramundane vision) can see or communicate with devas, there's no point in really wasting too much time speculating about them. The devas
were apparently believed by the ancient Brahmins (now modern-day Hindus) to be powerful gods and goddesses worthy of worship and sacrifices. They even believed one of these beings, named Brāhma, was the creator of the universe. But the Buddha ridiculed such beliefs as false. So the devas
have no real important place in Buddhism - they exist, but aren't worthy of worship. It might be accurate to then call Buddhism "non-theistic", because even though the Buddha taught that godlike beings exist, he also taught that they are not worthy of any special consideration or attention.