Our society is full of people who have fallen in one way or another, and what do we do with these people? How many good acts make up for a bad act? If you're a Nazi war criminal and then spend the next 40 years doing good deeds and feeding the hungry, does that make up for being a concentration-camp guard? I don't know the answer, but these are questions worth thinking about. I want there to be a possibility of redemption for us, because we all do terrible things. We should be able to be forgiven. Because if there is no possibility of redemption, what's the answer then?
There is, in my opinion, a fundamental issue here about the nature of good and evil that often gets expressed wrongly, or at the very least incoherently. As tempting as it is for us to believe so, good and evil are not things you can place on scales so that a certain variety of good "cancels out" a certain variety of bad. Much of what Martin himself says amounts to that: if there are people who have ostensibly made as many reparations as they can and are still hated for what they have done (as he cites), that tells me those things are not going to revolve around how much or how little, or even to whom.
I've mentioned before a parable, one from the Buddhist canon, about a man who finds that his children are trapped in a burning house and uses a Big Lie trick to get them to run outside (hey, there's all this candy and other cool stuff out here, come and get it fast!). People misinterpret this story to mean that it's OK to lie to someone as long as it's for a larger good, but that's not the point at all. The point is twofold: sometimes you simply do what you have to do to make things right; and — more importantly here — the fact that you are trying to do something to make other things right doesn't mean you're exempt from the consequences of your actions. Repercussions happen anyway, no matter how many good deeds you try to put in their way. That doesn't mean you shouldn't try to do them, only that you shouldn't bank on them being your Get Out Of Karmic Jail Free card.
The line about the Nazi war criminal is another good one in this respect. If a Nazi war criminal spends 40 years after WWII being an ostensibly good guy, that doesn't change the fact that he was, at one time, a war criminal. Those actions still have to be accounted for in some form, in the same way that if you smoke for 40 years and then quit you can't expect to not experience any of the lingering health effects of being a lifelong smoker. And what's more, if the guy has been doing good deeds for 40 years out of a genuine sense of repentance, he's going to understand that someday, someone may well walk up to him and say "Excuse me, but you murdered my whole family when I was a boy," and he's going to know, in his heart, there is no way he's going to be able to brush that off by saying "But look what I have done for the world ever since!"
Should you not bother to try to find redemption for doing terrible things? No, of course not; it's well worth it. But you have to go into it knowing full well what it's actually about, and the one thing that floors people the most is when they discover it actually has nothing whatever to do with them.