Manny says that angels die and their souls are extinguished. For a series which relies so much on Enochian and Kabbalistic lore, this is surprisingly quite wrong. The lore states that the difference between angels and humans is the fact that angels, while they do have spirit - the "essence" of God - unlike humans, they do not have a soul. This is supposed to be part of the reason for Lucifer's jealousy over humans and which led to his fall.
Constantine says the preacher "was bit" by a snake, which is an Americanism. The character's English; he should have said "was bitten."