It is a statement of fact that the current dictionary definition of agnostic is a person who believes that nothing is known or can be known of the existence or nature of God. Ipso facto anyone claiming to know anything about a deity is not an agnostic. Your subjective and unevidenced anecdotal claims about personal experience are irrelevant to that.
You also failed to address the argumentum ad ignorantiam fallacy you used, So whilst you may be content to make irrational arguments, and ignore what this infers, I cannot.
You also made a false accusation that I had defended the possibility of theism, yet despite being asked twice to offer even a single example, have failed to offer any quote from me to support this. What else can one infer but that this was either an error or mendacity?
No they certainly don’t change all the time, though overtime some words do change, and etymology whilst fascinating does not change the current definition, which reflects common usage.
The dictionary definition reflects common usage, so why would I accept your subjective opinion based on vague and unevidenced anecdotal claims for personal experience? Not only is this is exactly the kind of theistic arguments I reject all the time, but your claims were sweeping absolutes, and when I offered a qualification to help you, that some agnostics themselves wrongly misinterpret agnosticism, you simply ignored it.
Now of course you can believe the moon is made of cheese if it makes you happy, but your claims of personal experience of agnostics are anecdotal and unevidenced, and would not apply universally anyway since they are subjective, and they contradict the dictionary defection of agnosticism which reflect common usage, and your arguments are irrational, using an argumentum ad ignorantiam fallacy to imply that a lack of evidence or proof for a deity, proves it doesn’t exist.
Agnostic
noun
- a person who believes that nothing is known or can be known of the existence or nature of God.
Now compare that with your claim here:
By definition an agnostic can make no claims about any deity, so if someone claims a deity is possible, then they have ceased to be an agnostic, at least in that instance. If you have misunderstood them however, and all they did was claim a deity might be possible, which is the same as saying it might not be possible, then they have no actually made any claim to know whether a deity is possible. I think perhaps your sweeping claims and absolutes, and the poorly worded arguments are just a poor use and understanding of language, time here might remedy that, but only if you are prepared to keep an open mind.
You also didn’t address your risible claim to know what will be known in the future.
As I said it is simply risible to claim to know what may or may not be known in the future, with or without the absolute certainty you used, which merely indicates a closed mind. As I said earlier you’re confusing hubris and hyperbole with confidence, my confidence directly reflects the amount of objective evidence that supports any claim, no matter what that claim may be.
You should stick around, and read some of the debates that are recorded here, it will help you enormously I think to better understand what strong well reasoned arguments look like and why.
For example did you even read @Whitefire13’s or @Cognostic’s posts? They both explain a fundamental error in epistemology that you’re making here. Disbelieving a claim is not the same as making a contrary claim, and whilst the former can rationally be based on a lack of knowledge, the latter cannot. Basically if we cannot know whether a claim or belief is true, then we can rationally disbelieve it, but we cannot rationally claim it is untrue. this would apply to all unfalsifiable claims of course.
… there could be, but doesn’t give a rat’s ass - or was one and it died (caused the Big Bang 
)
Cheers carry on your debate.