Dark Matter, Dark Energy, and Atheism

When my son was about 16, he asked me if I was sure that God doesn’t exist. I replied that I was not absolutely certain about this; but that I was also not absolutely certain that no far-off planet is continuously orbited by purple pigs wearing pink tutus. With no evidence for either God or the purple pigs, both seemed to me equally unlikely.

Theists believe, based on faith, that God is everywhere, including our bodies and minds. Can we atheists ever believe in the presence within us of something(s) that we not only can’t detect, but is not even a constituent of our physical bodies? Dark matter and dark energy are good candidates for just such entities. The normal matter-energy in the universe (our bodies and everything else we can detect) is a tiny fraction (c. 4%) of the total matter-energy. The rest is about 23% dark (no interaction with light) matter and 73% dark energy (which pushes the universe to expand). Both dark matter and dark energy permeate our galaxy and hence us, but have no apparent physical effects on us. So if these entities don’t directly affect us, why should we believe in them? Because recent astrophysical observations of the universe have yielded strong evidence for the existence of both dark matter and dark energy. If equally good evidence for either God or the purple pigs were produced, then I would believe in either (or both) of them.