What Jan means? Jan is just trolling, trying (very successfully) to keep all the board's idiot-atheists crazily barking.
Be that as it may...
'Denial' in the epistemological context means declaring an assertion to be untrue.
Is denial that strong a proposition, though? If this is the case then many atheists do not "deny" the existence of God.
In the case of assertions that God, pixies or pink unicorns exist, denial would be the claim that they don't. And in the case of atheist assertions that they don't exist, denial would be the claim that they do. Either way, the denial may or may not be correct, provided that there are good reasons for taking a position on the reality of these things.
So agnosticism is a non-denial position?
Logically, denial seems to simply be the application of the 'not' operator ~ to whatever proposition is being denied. That's all I read the Greek 'a-' prefix in 'atheist' as doing, expressing 'not-theist'. It needn't be read as 'without' and can just as correctly be read as 'not'.
This is where it gets somewhat confusing, as in a "belief in X" the denial could be either "not-belief in X" or "belief in not-X". As we both appreciate, there is a syntactical difference: Is the negation / denial of "to eat a banana" either "eat a non-banana" or simply "to not eat a banana"?
More recently, the word 'denial' has taken on a new and more tendentious meaning derived from Freudian psychology, the idea of individuals insisting on the untruth of what should be obvious truths that they find threatening and don't want to face. So the word 'denial' has taken on a new perjorative and rather insulting meaning that it never used to have. That's the usage that we see today in phrases like "science denier".
This is where I think Jan is coming from, although I do await his confirmation one way or the other, and a fuller clarification from him, on the matter. It seems he thinks denial is to turn away from something that is objectively real, rather than simply to not belief as real something that is subjective.
To deny that Mt. Everest is the tallest peak on Earth seems different than denying that the Mona Lisa is a beautiful painting. The former is denial of fact, the latter is denial of subjective opinion.
In real life, it's often justified and entirely correct to deny particular propositions, provided that there are good reasons for doing so. If Jan wants to make a convincing argument that atheism is 'denial' in the tendentious Freudian sense, then he or she needs to make a convincing case that God's existence should be obvious to everyone.
And it should also be pointed out that Jan can just as easily be accused of 'denial' of the non-existence of God. Perhaps the truth of atheism (assuming it is true) is something obvious that Jan just can't face.
I still see denial of proposition X not as the claim that not-X is true, but simply as not being in a position to accept that X is true (irrespective of whether one claims not-X is true or not).
But I (still) await Jan's clarification of his usage of the terms.