The enemy of my enemy is my friend.
Tyrael's enemy is Diablo. Your enemy is Diablo. Therefore he view's you as someone on his side. You are not actually a champion of light, nor are you a champion of dark, you are a champion of humanity, of Sanctuary.
Good, in this game, is a relative term at best.
Very well said. I agree so much, I contemplated putting it as my sig. But then I thought against it lol. Lets just say that your sentences got a nomination lol.
And the destruction thing... well, I'm not sure. But what PhrozenDragon said about the pile of rubble is a good explanation too. I'd have to agree.
But, the Death thing... just think that it makes perfect sense for there to be a Lord of Death. Man fears it, it can be gruesome, and is the opposite of life and love. It could very easily be an evil thing. But yet its not, its a 'good' thing. I'm not saying it shouldn't be, I'm just pointing out the similarity and how the line between 'good' and 'evil' is oh so thin.