In a discussion I was in recently, someone made the common claim that it would be morally abominable for God to have the ability to save all people but only in fact save some. If God has a plan of providence, as Christianity traditionally has said, and that plan includes exactly what will happen down to the level of what sparrows will eat on any given day (as Jesus seems to me to state in the sermon on the mount), what evil kings will do in their pride in order to punish God's people (as the prophets seem to me to state), and which people will be counted among those who believe (as the book of Acts seems to me to state), then if it also includes which people won't believe Christian thinks God is morally abominable, whether that leads to an eternal hell or just annihilation. The claim is something like that, anyway.
There's a lot that could be said about this claim, and I don't have the time to treat it comprehensively, but I find the move to be interesting given another common philosophical claim that I've seen made against the most common Christian view historically on the atonement, i.e. penal substitution. The claim is often made that it would be wrong for God to use Jesus, an innocent, to take the sins of humanity, because then we're not really being atoned for. It's true that someone is dying for our sins, but it's not justice according to this objection, because no one is getting what they deserve. Jesus is wrongly killed, and we're unjustly not getting what we deserve. How could a just God allow that?
What's interesting about these two objections to what I consider to be standard Christian views is that they can't both be right. If it's wrong to allow Jesus to die for people and thus have the people not get what they deserve, then it can't be wrong to allow people to go to hell when they could be saved. If it's wrong to allow people to go to hell when they can be saved, then it can't be wrong to allow Jesus to die in the place of sinners who would otherwise deserve to suffer eternally in hell. Those who find themselves attracted to both objections face a serious inconsistency. I can't even imagine how the same motivational structure could produce both objections unless they stem just from the motivation just to undermine Christianity at whatever cost, even if it's the cost of inconsistency.
Now I haven't said anything against either objection. As I said, I don't have the time to work up a careful response right now. It just occurred to me that these are both extremely common criticisms of Christian views that I find among philosophers, and they seem to assume contradictory intuitions about the relation of justice to people's deserving punishment.
I also want to point out that there are other arguments against substitutionary atonement that focus on the mere substitution element but retain the penal element (see Wink's post on that), and there is at least one I know of that focuses on a different aspect of the penal element, namely that it would be wrong to kill an innocent Jesus, but I'm just thinking of one common argument the penal element of the atonement that I think can't be maintained together with the criticism of hell that I started this post with. I see both sorts of arguments from philosophers in the current climate, and I don't think the two could very easily be made consistent. It seems to me that you can't say that penal substitution is philosophically untenable because it makes God unjust for allowing some to be saved who deserve punishment they never get and then to go on and say that God is immoral for allowing any not to be saved. I'd be very surprised if there aren't people who say both things, but I don't see how both can be maintained.