["Alternative people" isn't a phrase that makes much sense to Castiel (alternative to what?), but given what he already knows about this case, it's easy enough to fill in the blanks. Dean means people who prefer intimacy with the same sex.
It's true that humans will find any reason to hate each other, even the smallest and most trivial of differences. Castiel's seen that himself, and while Dean doesn't get the sentence out, he doesn't need to.
Castiel remembers the way he'd punished those church-goers for spreading hate when they should have been spreading love. It's not something he ever likes to think back on, and the memory is enough to put him into a sober mood.]
shh it's okay i forgot about them burning the key
It's true that humans will find any reason to hate each other, even the smallest and most trivial of differences. Castiel's seen that himself, and while Dean doesn't get the sentence out, he doesn't need to.
Castiel remembers the way he'd punished those church-goers for spreading hate when they should have been spreading love. It's not something he ever likes to think back on, and the memory is enough to put him into a sober mood.]
... Well, we'll need to go find his remains.