I might be mixing up my metaphors here, but freedom is Nu-Mantia is "reach heaven by violence." Of course, that last bit wasn't necessarily meant to be taken literally... even though the person who said it clearly took it literally himself...
Either way, wonderful explanation from proweler. In terms of our society, we would view Pelinal as a horrible, despicable being--but since we're not being oppressed by a race that tortures us for the sake of art*, we can never know exactly what was going on in the minds of the people who Pelinal sided with (and of course, getting into Pelinal's mind is an exercise in madness anyway). Interestingly, our own society has plenty of historical figures who would be judged rather harshly by modern standards, but whose importance to society is such that we venerate them instead. It's not like Pelinal's case is something that only a universe like TES could create (in terms of his popularity by later generations, that is; obviously the real world isn't liable to bring us a god-built construct from the future any time soon, or at least, so we can hope).
*Note that we only know this through the propaganda of the Divines religion; it's probable that it happened, but it's not certain that it happened on quite the scale that The Song of Pelinal and The Adabal-a would have us believe.