Gamma rays were discovered in 1900 by French chemist and physicist Paul Ulrich Villard.
Before then, gamma rays simply did not exist. Because there was no proof. You could travel the world over, and read every piece of scientific literature in existence before 1900 to your heart's content. But you would neither see this magical, so-called "gamma ray," nor have any scientific proof anywhere, whatsoever, that gamma rays exist.
Therefore, by all scholarly logic and rational scientific reasoning, gamma rays did not exist. If something cannot be shown or proven, it simply cannot exist and you're a fool to even consider otherwise. I learned this solid, infallible logic from atheists.
Now with that being said, are there crazy fucked-up religious nuts who I would just as soon avoid like the plague? Absolutely. God and them are two entirely separate entities.