religion has often replaced scientifically proven facts, wich is mainly due to religions powerful ability to not have to make sense and still be acceptable.
now as for religion actually disproving science, those occurences can be counted on zero hands.
it basically is, although most distilled water does contain a small amount of contaminants, so it would likely not count as cemically pure.
as for drinking it: i've found this article, according to which you shouldnt expect health problems, provided you eat a healthy diet. As most minerals we consume come from our food, not the water.
then again it supposedly tastes bland, is more expensive than tap water (provided your tap water is safely drinkable) and why even take the risk?