I think this book was just alright, but maybe better than I expected in some ways. This is my first book to read by Piper, though I've obviously heard a lot about him and have read excerpts of things he's written before. I really like the topic of the book, and I think it's intriguing and an important question that most Christians will/should consider at some point in their Christianity. Actually, the interesting thing is that even while I was reading it, a brand-new believer asked me the same question. I can't say my answer was the exact same as Piper's though.
I think that Piper generally does a great job of answering the question and dissecting it into its various nuances. He seems to have a pretty good command of the issue at hand when this question is asked. Personally, I don't think a view on Hell (either annihilationist or otherwise) needs to be in any way defined to answer this question. But I can see how someone of Piper's theological persuasion might see that as inherent in this question. One of the first things I didn't like about the book though was that his introduction was entirely too dogmatic. He confronted all the major arguments and stated all his main conclusions right at the beginning, and he did it as if his ideas were both obvious and indisputable. I don't appreciate that line of argument or reasoning. I was happy to see that throughout the book, he actually did converse with many of the main contrasting ideas, and as far as that's concerned, his footnotes were also much more fair to dissenting ideas/opinions than the actual main content of the book. I appreciate at least that. Also, as he's considering many of the arguments, he seems to alternate between some proof-texts and some actual consideration of the internal context. Obviously I don't appreciate the proof-texts, but I certainly was happy he went in-depth on some aspects of the context and I applaud him for that.
However, my main overall problem with his approach, that doesn't seem to let up anywhere in the book, is that he seems to believe all theological issues, and certainly this particular one, have defined and clear answers in the Bible. He doesn't seem to take the human element into consideration, along with the idea that just maybe WE (which includes the Bible's authors themselves) don't actually know the full answer to this question. He seems to think this is a sort of "mathematical" question, where if you find 1 and 1, then you know you've got 2. When I read the beginning of Romans, I can see that Paul is making a reasonable/logical appeal from what he can see and from (I assume) some inspiration of the Holy Spirit. But when he gets to Romans 2:15, the translation variously reads "sometimes defending" or "perhaps excusing" them on the Day of Judgement. It sounds like Paul is taking a guess here and the guess seems to be that maybe God will take mercy (on the Day of Judgement) even on those who haven't known the specific history of Jesus but who have followed and submitted to what God HAS shown them. It doesn't sound like it's set in stone, but there's no reason to assume it should be. We won't be the judges, so why should we expect to have a full criteria of judgment revealed to us? Especially when we consider that one of the overarching and most consistent descriptions of our judge is that he's "merciful". Paul wrote letters to churches, about how to conduct their lives and how to believe in Jesus. He didn't write theological textbooks. Why should his letters be following classical (i.e. mathematical) parameters of logic? So, it definitely comes off as dogmatic and unnecessary for Piper to require a black and white answer to this question, and to ignore the perfectly human aspects of the Bible that seem to offer opposing thoughts.
My last contention is Piper's claim to speak "on behalf" of missionaries, claiming the missionary cause is defeated by believing God has mercy on some who've never heard his historical name. As a missionary myself (a long-term one, not just a show-up-every-now-and-then) one, I'll say that's certainly not the case! It's true, as Piper claimed, that believing God might have or have had mercy on people who've never had the opportunity to hear his explicit history takes away some of the urgency in the work. But I think that's both appropriate (certainly more balanced) and gives God even more glory (Piper's own stated objective)! It helps keep me from rushing around like a clown thinking it's my urgent work to make sure no one goes to Hell. Instead it puts the focus back on God and seeks to observe and participate in the work he's already doing. It's his saving work, and though he chooses to use me in it, it doesn't rely on me. It also certainly does broaden my perspective of the Gospel, and removes it from the limitations of individual eternal destinies but allows me to consider what God's plan is for this whole world! That makes the message I share both more life-giving and more in line with what we read in the Bible. And it's worth sharing (and motivating me to share) regardless of my consideration that God may have already been working on (and perhaps giving mercy to) some I'm sharing it to, or some in the community who've already passed on but who've helped lay a solid foundation for those following them to receive the message I'm bringing. I certainly believe the historical consideration of God's work in Jesus is more fulfilling and life-giving than any general revelation, even if God might/does take mercy on those who've had nothing more than the general revelation (or some specific revelation too that was less explicit than the historical one we have now), and that motivates me to share! It also keeps the focus on WHO is the judge: Jesus. Not our preconceptions of the things that limit his judgment. And I'm saying all this as an active missionary. It doesn't undermine my foundation in any sense, but undergirds it even more strongly with a broader view of who God is and what he does in this world.
Finally, I appreciate that through this book I've come to see that my own views on the matter are well-represented within Orthodox Christianity. And there's a name for it: "inclusivism"! While the nuances of my belief on it may not be entirely the same as those with that label, it's nice to know there are plenty other Jesus-seeking Christians who've come to consider that this sort of work might be or is part of his plan.
Overall the book brings up a good question and in some areas considers it thoroughly. However, I think the author's personal approach to the Bible somewhat limits his consideration of the bigger picture and leaves some areas to be disagreed on. Also, I think he could use some improvements in his manner of writing, making it more enjoyable and accessible. But what he did achieve was short and fairly comprehensive and for that I appreciate it. I'll definitely give some of his other books a chance (especially considering they're so often free digitally) and at least now I have an idea what I'm in for, perspective-wise.