What proof or evidence do you have that atheism is true and correct?
What proof or evidence do you have that atheism is true and correct? is a question that YouTube evangelist Shockofgod likes to ask atheists. He often claims to have been banned from call-in shows and forums for asking it (in reality he's banned because he just repeats it and never listens to any answers) and cites this as conclusive proof that atheists don't know the answer.
In these circumstances it can be ominously described only as The Question. Its use can be effective, but only when combined with a disregard for generally agreed conversational etiquette; because people answering it tend to get bogged down in trying to patiently explain that it is impossible to prove a negative, how burden of proof works and explaining the nature of evidence. While they are explaining these issues, ShockOfGod simply shouts the question at them again.
 Actual answers
It's certainly arguable that atheists don't have proof that their lack of belief in God, or their belief that there is no God, is "true and correct". If there was conclusive proof one way or the other, the question probably would not be so much debated. But despite this, the question is far from unanswerable as Shockofgod's ego suggests. The answer is more convoluted than he would like and certainly doesn't provide the sort of answer he would expect. This is common with many amateur theologians or woo-pushers, who use loaded questions all the time. Contrast it with the question "can you give one example of a mutation that increases information in the genome?" which was once asked to Richard Dawkins, or Harun Yahya's Ask Darwinists to see that there is a certain style to such questioning that suggests the asker knows the answer is convoluted and that the question is probably not even wrong, but they ask the question anyway to score some points.
 Burden of proof
First, let's actually look at the question. The main problem with it is that it attempts to shift the burden of proof from the people proposing an idea (i.e., "God exists") to those who reject the idea. The question assumes God must exist, and therefore anyone rejecting God's existence is required to present their evidence. This is problematic because such presuppositionalism works for anything and everything. When proposing an idea there are countless alternatives that could also be presumed in the same way - perhaps it's invisible goblins, not God, or perhaps it's Wotan, not God - so, unless you have at least a shred of supporting evidence for your presumed idea it is almost certainly wrong. In other words, there is an absence of evidence. Where one would reasonably expect such evidence to be abundant, an absence of evidence is evidence of absence.
This is why the burden of proof exists in the way that it does, and that it's the job of those who maintain that God exists to provide evidence for their beliefs. If convincing evidence has not been provided to back up a belief, then people who do not subscribe to that belief do not need to justify their lack of belief. This applies to most, if not all, assertions: Atheists have no more need to "prove" that God doesn't exist than they need to "prove" that Father Christmas or the tooth fairy doesn't exist. Turning the question around, an adherent to Christianity (much like Shockofgod himself) has no need to disprove the multitude of other gods that have existence in human history before settling on the Christian God as real.
 Evidence for God
Given the burden of proof discussed above, it is possible to present some evidence for the existence of God. It is then up to the rejecter to state why such evidence is insufficient. This is a valid discussion point. The existence (or not) of miracles and the answering (or not) of prayer is frequently discussed. Atheist philosophers have discussed these numerous times, and a full understanding of what counts as effective evidence and what is personally convincing evidence is all part of the debate. While this sort of activity is valid, Shockofgod's question skips it out entirely. It leaps straight in at proving a negative by asking to prove atheism is "true and correct", which isn't really possible, and ignores the more subtle and productive discussion the burden of proof facilitates.
 So why are you an atheist?
Before becoming atheists some individuals sought God, prayed, reflected and studied the world around them without finding any gods. If you are told that something exists, and is easy to find, and you look for it, and you don't find it, that must be strong evidence that the object in question is not real. So it is with God. Unlike the Loch Ness Monster, whose elusiveness can be explained away by being famously shy and living in a very large, dark loch, God is supposed to be everywhere, and to respond to those who call on him. Therefore if a reasonable search draws a blank, something is amiss. There is even an article explaining the concept of Evidence of Absence on that other wikipedia.
Does the atheist have proof? Of a negative? Certainly not. But does the atheist have evidence? Yes.