I think you're right that there's such thing as someone who only wants to save someone from eternal hellfire in their conversion attempts. A lot of the time, though, I can't help but see a level of wishful thinking involved in the idea that non-believers will burn in hell. It's no small amount of Christians who use "you're going to hell as a threat!"

I don't think all Christians are bad people. But the sincerely held belief that people who don't believe in Christ actually deserve an eternity of hellfire--it's one of the great ills of the Christian religion and it's a kind of thinking that really deserves to be challenged.