Atheism is not meant to function like a worldview or a religion. It is better understood as a thought process that reflects one’s honest assessment about knowledge as well as probability based upon evidence for a claim. Pertaining to knowledge I will not presume to know what is vague and closed off to me personally as well as for humans collectively.
The God question is undoubtedly the least agreed upon subject in history as well as in the present. It is the weightiest claim with the weakest set of criteria from which to discern from and make a basic decision about. Subjective explanations simply fail at making God a reality that is readily identifiable for all. If there is not a process that can effectively bring one into the uncontested presence of a God then uncertainty and doubt is justified. The mass variety of contradictory answers that are given across the board is reason enough to suspend judgement on this matter.
The probability of miracles is low enough as it is, but even if we grant strange phenomena that appears to be supernatural in nature it is still a far cry to even attempt narrowing down on which God to believe based upon such claims. The fact of the matter is that miraculous claims are inherently self defeating even when we allow the possibility! Competing religions write off the claims of one another as a rule and people are rightly skeptical of such tall claims from the onset. Why would a wise and all knowing God choose miracle claims as a reliable way to conclude what is true in the world? Soak in that question for a while.