Atheists are being attacked by presuppositional apologists, like Sye Ten Bruggencate and Eric Hovind, telling us that in order to know anything, we need God. Telling us, that the atheist worldview (whatever it is) viciously circular, as it uses our senses and reasoning to justify our senses and reasoning. While the theists have God to justify their senses and reasoning. So we have to presuppose God in order to make sense of the Universe. In other words, they are attacking the very bases of atheist epistemology. They asking questions like: tell me something for certain and how do you know it. And questions like: can you be wrong about everything you claim to know. These questions can be intimidating even for a seasoned atheist. But do not fret, here comes Epicurean Epistemology to the rescue.
Epicureans were one of the four Hellenistic schools of philosophy. They were hedonist of the sophisticated type, not like the Cyrenaics. Epicureans had comprehensive metaphysics, including epistemology.
In Epicurean Epistemology knowledge is based on the senses. Why on the senses? Because they cannot be wrong!
One could bring up the classical objection, a stick, or an oar put into water half way, looks bent. But we can feel it with our hands, that it is not bent. One could say, look your eyes are deceiving you, as the stick is not bent, but it looks bent. As an Epicurean, I would say, not so fast. My eyes are not deceiving me at all, as they show me exactly what they should. Because in realty a stick put into water half way, should looks bent. So, my eyes are reliable, as they showing me what a stick put into water half way looks like. In fact, if I would see a straight stick, than my eyes would deceive me. Further more, I can use my senses and reasoning to find out, why a stick looks bent, when it is put into water half way. I could find out, that the reflecting index of air and water are different and that makes the stick appear to be bent. Please note, that I used nothing but my senses and reasoning to come up with the explanation. It was not an infallible all knowing eternal being, that revealed to me why a stick looks bent.
We could say the same thing about the other classical example of, why we should not believe what our senses tell us: The square tower looks round argument. Again, our eyes show us exactly what a square tower looks in a distance. And again we can and do use our senses to verify that the tower is square, by going closer to it.
Even the extreme case of dreaming, or being in the matrix, does not show, that our senses deceive us. As it is expected, that if someone in a deep dream, or in the matrix experience what is fed to their senses and brain. We may not have the opportunity, but if we would, we could use our senses to work out what was the exact cause of our experiences.
From the above, we can see, that our senses are rock solid base for our epistemology, that is our knowledge. Furthermore, we have no other way to get information about the world but our senses. Therefore the ultimate arbitrator about what is true, what exist etc, is nothing but our senses.