Since this is the Skeptical Zone, I think it is appropriate to apply a little skepticism to atheism itself. How could anyone know if they were deceived by an evil demon into believing that God does not exist? Furthermore, if a person was trapped inside a matrix of evil lies and deception, is there anyway to escape and come to know the truth about God?
Certainly it is more likely that an atheist could be deceived by an evil spirit into not believing in God, than it is that all of us could be completely deceived about everything as Descartes proposed in his Meditations. Hence, this is an argument that the atheist should take seriously.
It should also be noted that the empirical sciences are of no help here because for the deception to be successful demons could not leave behind any testable evidence. If there was proof that demons existed, that would constitute strong evidence for the existence of God. So demons must remain hidden and work through nonphysical means.
So what would the deception look like? It would begin by asserting that all knowledge is acquired through the senses with the aid of the scientific method. Scientism, materialism, and naturalism provide the foundation for the deception. Knowledge of God is ruled out a priori.
Secondly, it would promote immorality as normal. Nothing keeps the mind from thinking about God any better than the vices of greed, lust, and pride.. A culture that promotes mindless consumerism, sexual promiscuity. and narcissism is perfect for this.
Finally it would mock religion in general and seek to place restrictions on religious speech and expression. Militant secularism and freedom from religion would be promoted as necessary for a healthy society. If a person never hears about God, then it is much less likely that they will think about God or believe in God.
Since all the elements of the deception are already in place, only a fool or a willing participant in the deception would refuse to investigate the unthinkable alternative. Maybe God actually exists.
Escape from the deception can come about in many ways. The first step is for the atheist to acknowledge the fact that he might be wrong and may have been deceived.
A second step is to consider the fact that everything that actually exists either came from something that actually exists or, is self-existent and exists eternally and immutably. The material things that science studies are all made of parts that can be put together to make something and broken apart and reformed to make something new. There is nothing in the material world that is eternal or unchangeable. The universe that we know is not eternal, it came from something else. That eternal something else that produced our universe cannot itself be composed of material parts for then it would not be self-existent or eternal. It must be immaterial. The immaterial, eternal, and immutable something else is what philosophers call God.
But what sort of being is immaterial and eternal? The one thing that we know of that is like that is our own minds or souls. Our minds are not bound by time. We can think of the past, the future, and the timeless. Our minds are not bound by space. Our bodies and our brains are in one place and our experience is limited to that place at that time. Our minds however, can be anywhere and we can think about anything that we choose to think about including abstract immaterial things that are not in any particular place or time. Most importantly we can choose to think about God.
Religion is the result of our thinking about God, and even though most of our thoughts about God may be wrong, it is possible that God is also thinking about us and wants us to know him. That is a possibility that is worth investigating. I believe that everyone who seriously seeks to undertake this investigation will eventually know the truth about God and be freed from all deception, but first you have to want the truth and nothing but the truth,