That's the summary of the chapter, as well as the title. Rob is going to argue that eternal life/heaven/life in the age to come/God's kingdom/God's will begins now, in this life and continues into the next.
It's not really a radical position to take.
Rob makes the not-so-obvious point in the middle of the chapter, though: What you believe about the future shapes, informs, and determines how you live now. (46). And that's what this chapter is really about - digging through the Scriptures to present to the reader a very Jesusy vision of heaven. This will mean we get a very Jewish vision of heaven. And that's where some people may get very uncomfortable.
Rob starts the chapter by describing an ugly picture that used to hang on the wall in his Grandma's house. It represents popular notions about heaven, notions that Rob wants to push back against. To start his argument, Rob begins in Matthew 19, a story where a Rich Man asks Jesus how to enter into eternal life. From there Rob will unpack his chapter, tackling three big themes: our notions of "eternal life," "treasure," and "heaven." (29)
Rob tries to argue that the traditional exegetical interpretation for "eternal life," which is the Greek word "aionon," fails to incorporate the Hebrew concept of "olam habah." Aionon gets translated "eternal life" and we think time without end, minute by minute, day after day, century following century without end. But Rob points out in the Old Testament that "olam habah" carries with it the idea of "life in the age to come." He implies that we're missing the point of olam habah by focusing on a traditional interpretation of eternal life.
Different scholars have pushed-back against Rob and his attempt to add a new nuance to "aion." However, I think the point still stands: Jesus is a Jewish prophet who's words were recorded in Greek. Whatever the Greek word "aion" traditionally means, we have to take into consideration what the Jewish tradition meant by the idea Jesus was addressing. The New Testament is written in Greek, but Jesus is Jewish - so he might be recorded as using the word "aion", but it's likely he was referring to the Jewish idea of "olam habah." Rob is not convincing in his case to present a nuanced meaning to "aion." But I don't think it undermines his bigger points about eternal life.
Rob walks through the OT prophets to make points about what "life in the age to come" would be like. Isaiah 2 & 25, Ezekiel 36 and Amos 9 are used as examples of how God's prophets described eternal life, or life in the age to come. He summarizes thus: "It's here they were talking about, this world, the one we know - but rescued, transformed, and renewed." (34) This is what Jesus and the Rich Man had in mind.
This provides the transition to the discussion about "treasure in heaven." Rob phrases it like this:
How do you make sure you'll be part of the new thing God is going to do? How do you best become the kind of person whom God could entrust with significant responsibility in the age to come? The standard answer was: live the commandments. God has show you how to live. Live that way. The more you become a person of peace and justice and worship and generosity, the more actively you participate now in ordering and working to bring about God's kind of world, the more ready you will be to assume an even greater role in the age to come. (40)
When Jesus lists the commandments to obey, he lists five of the final six, omitting the one about coveting. The rich man insists he's kept the five Jesus listed, but he can't commit to keeping the sixth one. As Rob puts it, Jesus is inviting the Rich Man to use "his wealth to move creation forward" and if he can do it, "he'll have 'treasure in heaven.'" And so ideas about reward and "treasure in heaven" imply direct connections between life now and life then. The reward of quitting coveting now begins now - and it carries over into the life to come. To the degree that we enjoy the reward of living the commandments now, we can appreciate the rewards of heaven now.
So what is heaven like then? "Heaven comforts, but it also confronts."(48) Rob points to John the Revelator's reference to Isaiah, about a day coming when there will be no more tears or pain. Comfort. But then Rob points to Paul and his insistence that on the day of judgment some will enter heaven "even though only as one escaping through the flames." "Flames in heaven." (49) Heaven confronts. To enter heaven is comforting, then, but there is some kind of purification that must occur in order to prepare each human for life in the age to come. Purification implies transformation, which implies change - which sounds a lot like repentance.
It's important, then, to keep in mind that heaven has the potential to be a kind of starting over. Learning how to be human all over again. Imagine living with no fear. Ever. That would take some kind of getting used to. Soul would a world where loving your neighbor was the only option. So would a world where every choice was good for the earth. That would be a strange world at first. That could take some getting used to. (50-51)
Rob reflects that peoples confusion about heaven comes from their assumption that the change will be immediate. And that's where a lot of resistance is going to emerge to what Rob is suggesting about entering life in the age to come, about getting eternal life. What if it is not immediate, but something that takes time?
One last thing about heaven: who will be there? Rob goes to the story in Matthew 25 where Jesus distinguishes between two types of people. One group will assume that heaven is their destination, and be surprised when it is not. Another group will not consider heaven as their destination, and will be surprised when it is. Rob summarizes: "Heaven, it turns out, is full of the unexpected."
I'll let Rob give the summary of his own chapter:
...when Jesus used the word "heaven," he was simply referring to God, using the word as a substitute for the name of God.
Second, sometimes when Jesus spoke of heaven, he was referring to the future coming together of heaven and earth in what he and his contemporaries called life in the age to come.
And then third - and this is where things get really, really interesting - when Jesus talked about heaven, he was talking about our present eternal, intense, real experiences of joy, peace, and love in this life, this side of death and the age to come. Heaven for Jesus wasn't just "someday"; it was a present reality. Jesus blurs the lines, inviting the rich man, and us, into the merging of heaven and earth, the future and present, here and now. (58-59)
Rob seems to be attempting to invite readers to swap visions: their fluffly cloud, obscure and super-spiritual vision of heaven for an earthy, love your neighbor, feasting kind of heaven. If anything, Rob is trying to help people incorporate Jesus' Jewish beliefs about life in the age to come into their modern visions of what heaven might be like.
But Rob is also trying to make you reconsider about who will also be in heaven with you. We might be surprised at who Jesus welcomes in the age to come. But rather then focus on who is in and who isn't, Rob is pleading with people to start living "eternal life" now, live in light of the age to come now, be part of the answer to Jesus' own prayer: "...your kingdom come, your will be done, on earth as it is in heaven." It's this kind of activity that will make any kind of evangelism we do much more fruitful, much more Jesusy.