Angel of Death, like so many songs in heavy metal ("The Number of the Beast" also comes to mind), is so frequently misinterpreted it's saddening. It's written about Josef Mengele, but as Jeff Hanneman, who wrote the song, puts it:
I know why people misinterpret it — it's because they get this knee-jerk reaction to it. When they read the lyrics, there's nothing I put in the lyrics that says necessarily he was a bad man, because to me — well, isn't that obvious?! I shouldn't have to tell you that.
There's also the fact that Tom Araya and Dave Lombardo are of distinctly non-Aryan heritage. ;-)