PZ recently linked to a rather disturbing video on display on GodTube. I don't recommend actually watching it (though it is perhaps appropriate for Halloween), so I'll summarize. It's a fictional letter from a guy in hell to his living Christian friend asking why, oh why, wasn't he told about this ...Jesus. It's supposed to be a call to all Christians to start proselytizing to their friends, if they truly care for them.
Obviously, there are a lot of different things I could say about this, but my first thought was that hell isn't completely compatible with any sort of ethics that involves caring for others.
Let me elaborate. Hell (along with Heaven) is a sort of poetic justice, seemingly taken out of fiction and put into real life. Hell is supposed to be a motivator to do good, because your good actions here will be translated to good rewards in the afterlife. Why be altruistic? Because if you care for others in this life, you will get taken care of in the afterlife. In other words, altruism is justified because it translates to selfish goods at the endgame. Heaven and Hell: a possible basis for ethics?
I would argue that under this system, altruism doesn't apply to the afterlife itself. Consider a situation in which you have the opportunity to sacrifice a bit of your own afterlife pie in order to save someone else from hell. For example, maybe you had to fib a bit to get them to come to your church or something. Maybe afterwards, you could confess so that it wouldn't hurt your own eternal fate at all. Is it justified? Would it be justified if you converted people through threats? Through coercion? Through terrorism? Would it be justified to sacrifice your own soul by killing innocent babies before they have a chance to sin? Perhaps you were already convinced you were irrevocably going to hell, so you might as well help as many other people in the process.
I think it should be taken it for granted that none of the above are justified. Also, Hell only really provides motivation for altruism that concerns this life, not the next. Therefore, altruism is only justified and motivated under the heaven/hell system if you care for people's real lives, not their afterlives. It's internally consistent, at least.
But, shoot! It seems that excluding the motivation from heaven/hell, people still feel the need to be altruistic. Who knew? That's why you get people who care about your afterlife, and are willing to sacrifice simple civility to save you.
These people are clearly misled... but at what point did they make a mistake?