What exactly is agnosticism?
Agnosticism (noun) is under discussion; rather than agnostic as an adjective/modifier (usually used with atheism and theism; ex., agnostic atheist, agnostic theist).
My opinion? Agnosticism is cop-out from taking, or stating, a position vis-a-vis the existence of God(s).
Prepare for a wordy copy and paste from previous discussions......
Let's take a look at a logic based argument and definition of the various forms of atheism/theism - and the logical and intellectually dishonest cop-out of Agnosticism (noun) (where Agnsoticism is often used to side-step the consequences of actually taking/stating a belief position (e.g., atheism vs. theism)).
Background:
When considered explicitly, belief is binary.
When applied to the question/issue of the existence of God(s); either you have belief (that God(s) exist or that God(s) do not exist) or you have a non-belief (that God(s) exist) position.
However, the belief, or lack of belief, level does not have to be 100% certain, rather the belief/lack of belief level of certainty (or reliability and confidence) can vary with specifics within the belief/non-belief divide. One can be a gnostic (knowledge claim) atheist/theist, to some level of reliability and confidence less that 100% unity or certainty, and still define themselves as a positive/strong/gnostic atheist/theist. Additionally, with the claim of gnostic atheist/theist, one is also, implicitly, an agnostic atheist/theist. To muddy beliefs/positions even more, one can be a theist for a specific God or set of Gods, and, at the same time, maintain an agnostic or gnostic atheist position/belief towards other Gods.
The null or default state is the null hypothesis. The null hypothesis cannot be proven, it can only be falsified or rejected in favor of an alternate hypothesis with supporting justification for the rejection of the null hypothesis and the acceptance of an alternate hypothesis; where this supporting justification is based upon credible evidence, and/or supportable argument that is free from logical fallacies and which can be shown to actually be linkable to this reality, to some defined/required level of significance (or of reliability and confidence).
Argument/Definitions:
The hypothesis question is: Do Gods exist? (or as a hypothesis statement: Gods exist).
In terms of theism/religion, the null hypothesis for the existence of Gods is {non-belief in supernatural deities/gods|lack of evidence/knowledge to support a belief position}. This is the agnostic (where 'agnostic' used here is an adjective) atheist position; lack of belief or non-belief due to lack of evidence/argument or the failure of those promoting alternate hypothesis from credibility meeting their burden of proof. The agnostic atheist fails to reject the null hypothesis.
The gnostic atheist alternate hypothesis is that {(one or more) supernatural deities do not exist|based upon knowledge}. The gnostic atheist has the burden of proof to support or justify rejection of the null hypothesis, and to support belief or acceptance of this alternate hypothesis.
The theist (agnostic and gnostic) alternate hypothesis is {supernatural deities do exist}. The theist has the burden of proof to support or justify rejection of the null hypothesis, and to support belief or acceptance of this alternate hypothesis.
The Agnostic (noun) claims that one cannot know (and may never know), or that it is unknowable, if Gods exist. The Agnostic uses this lack of knowledge (or the premise that the knowledge is unknowable) to sidestep, apologize, or rationalize, the abstention of taking a position vis-a-vis the existence of supernatural deities/Gods. Since the claimed Agnostic fails to believe or accept an alternate hypothesis (either gnostic atheist or theist), they have failed to reject the null hypothesis; where the failure to reject the null hypothesis is the default or agnostic atheist position. This failure of logic, intentional or not, does, however, allow the Agnostic to be a functional atheist without actually accepting that nasty label of "Atheist," and also allows the Agnostic a route to sidestep/avoid defending their worldview from both theists and atheists.
As with Agnosticism, the same applies to those explicitly considering the existence of supernatural Deities/Gods but are still in the process of examination and/or are undecided. Until the explicit consideration reaches a point to justify or support rejection of the null hypothesis, the person fails to reject the null hypothesis and holds the null position, the position of an agnostic atheist.
Finally, the person that has not considered the existence of supernatural Deities/Gods for whatever reason (ex., age (infants/children), lack of exposure to theistic related concepts, inadequate cognitive ability), the person fails to reject the null hypothesis and holds the null position, the position of an implicit agnostic atheist.