God, yes, but who knows if he's telling the truth about hell or not.
Lucifer questioned God when he was told to look to Adam as (for the sake of the story) a higher rank than Lucifer. Lucifer's like, WTF God? This dude's a mortal, and I'm a fucking angel. God gets all pissed and sends him to hell and he becomes Satan who appearently so infuriated about getting kicked out of heaven, he spends eternity torturung condemned souls in pits of fire and brimstone.
Or is that what God wants us to think? Wouldn't God convince us that Hell is the most horrible place and fate anyone could end up with? Wouldn't Heaven be like a strict boarding school with a dress code declaring halos must be 6 inches from your head and robes must go down to the knees whereas Hell would just be like a frat house partying 24/7.
Lucifer stood up for what he believed in, and I don't think he was going to do what God told him after he was already kicked out of Heaven.
The worst thing Lucifer could to God would be make Hell seem like a funner place than heaven and heaven would go out of business (metaphorically speaking).
Just something to think about; I also thought it would be a lot of fun to discuss.