Do you mean Warcraft 2?

It is definitely in Warcraft 2, although it might have already been in Warcraft 1too, I can't remember.

2 or 3 yep

Here's the new quote. I tried to come up with one on the less difficult side, so that this thread isn't left barren for a day with no gusesses ;-).
"I have always believed that faith was measured in deeds, not words. And while many of my children worshipped my name, their deeds betrayed them."

Command & Conquer 3: Tiberium Wars and Kane's Wrath.
If I'm right, try to guess game that have this dialogue:
"Look like you're out of customers"
"Yeah, your gang took off with those... those well-dressed gentleman."

You were correct, it is from C&C 3, it's in Kane's entry.

Sorry Drelmanes, but that's from another one of my favourite games: Full Throttle, from the game start. Ahhh how I miss old Lucasarts dialogue, like the exhange that follows that scene:
"I've never liked noserings."
"Me neither, but someone dared me."
And by the way, my quote was from Bioforge so cheers from you too Carra.
Let's see if you guess the following one
"Nothing's real, we're all made of pixels and our brains are numbers."

Fable II.
New quote:
"Tis a sad state for Britannia when events such as these happen. Christopher was a good man. I hope that the villain is caught."
I'm tired, good night everybody...

It could be Ultima VII:Black Gate?
Maybe in Trinsic when discover the body of Christopher?

Yes, and the Trinsic healer is the guy who says that.

New quote:
I would really like to come with you!

I have no clue at all, man :(

I will give you a hint.
The game is in GOG catalogue!

You do realize that that doesn't narrow down the choices very much?
My guess is it's an RPG that GOG sells, probably one that I haven't played at all or that I haven't played in a very long time. It is probably NOT of the Fallout Trilogy or any of the sequels. I also nix Arx Fatalis, Spellforce, and all the Gothic games... Is it Septerra Core? Maybe one of Led's lines?

Yes, it is an RPG that is in GOG catalogue, but there isn't none of your bets.
Another hint: This game it's truly an oldie!