Because he has been listening to my phone calls. However, combined with recent Pharyngula and Freelance Genius serendipitous postings, it is also possible that I am broadcasting some sort of telepathy that is selectively received by those of similar minds on certain days of the year when celestial alignments are just right for a mind wave to pass through wormholes and burst forth into another human's brain within the same Hubble Universe1 in a Level 1 Multiverse. In an unrelated corollary, I was reading a Scientific American special report about parallel universes and I suddenly understood faith in a God and also the person with whom I dialogue in my mental conversations. The prior sentence's structure might imply that these two beings are one and the same, but that is not the case. I am talking to myself, but the myself in a different Hubble Universe anywhere from 2 to 10118 meters from my current Hubble Universe.
UPDATE: In other comic news, this comic is not at all a refutation of Decartes assertions about God.
UPDATE TO THE UPDATE: In a completely different kind of comic news, Eugene Mirman had a thing in the Onion's AV Club.
1 A Hubble Universe is the observable universe. This amount of space is limited by the speed of light and thus also limited in scope by the expansion of the universe which is happening at that speed.2
2 If I can get this crazy after only reading one third of an article about fairly complex physics without having taken physics at any level, why could I only acheive a barely passing grade throughout college? Perhaps the answer lies in the fact that I did not know to whom I was talking to in my head all those years.