How so? What thoughts would Nicodemus have had upon Jesus’ use of these words? Well, reference has already been made to the long-standing Jewish hopes of the kingdom of God, the resurrection of the righteous dead, and their God’s restoration of the fallen creation, but there is more. It has been made quite clear that eternal life, as Jesus uses it (as a first century Jew) and as Nicodemus understands it (as a first century Jew), has nothing to do with the idea of escaping the physical world so as to enjoy eternity in a state of dis-embodied bliss that could only be enjoyed by soul and spirit. No, that was Greek thought. That was pagan thought. To whichever culture such thinking is assigned, and though Jesus and Nicodemus (and the author of John) could certainly have been aware of that worldview, Jews were highly resistant to such ideas, and in general were fervently opposed allowing such ideas to creep into their particular worldviews.
The dominant Jewish worldview affirmed the absolute goodness of their God’s perfectly created (though fallen) physical world, whereas the other dominant worldviews of the day (Platonism, Stoicism, Epicureanism, Buddhism, etc…) largely held the physical world to be sub-standard and second rate. Judaism, in large part (though there were groups like the Sadducees that denied this worldview, though their denial may not have been completely legitimate and deeply held, perhaps owing to the fact that they were in collusion with the Roman powers---this is significant because they were partially charged with keeping peace and tranquility in Israel, whereas the hope of resurrection and restoration was very much a motivating factor for Israel in their long-running opposition, both passive and active, to foreign dominance) stood against “other-worldliness,” and embraced a “this-world” view.
It could be insisted upon with a great degree of certainty then, that when Jesus speaks of the kingdom of God and eternal life, He is decidedly not speaking to Nicodemus about going to heaven. In that same light then, the author would most certainly not be asking his readers to consider the possibility that Jesus is speaking about going to heaven, and thereby promoting an escape from this world---an idea rooted in so much anti-Jewish, anti-Biblical thought.
How can this be known? It can be known because “eternal life” is the language of exodus. Exodus meant more than simply leaving Egypt. Exodus, for Nicodemus (and for all who count themselves among the covenant people) meant rescue, deliverance, liberation, redemption, salvation, resurrection, restoration and more. Eternal life as exodus was a powerful notion. Exodus meant that Israel’s God was establishing His kingdom, through and for His chosen people, for the purpose of accomplishing His purposes for the world, through and for them. Exodus meant that Israel’s God was not only rescuing, delivering, liberating, redeeming, saving, resurrecting, and restoring the beings that had been created to bear the image of the Creator and reflect His glory into His world, but it meant that He was doing the same thing for the whole of His world (and by extension the cosmos) as well.
Therefore, it must be insisted upon that all of these things, for a first century Jew, when spoken and heard inside a long-running narrative by which a people defined and understood themselves and their place in the world, had a decidedly this-worldly reference. Thus, when Jesus said these words, and when Nicodemus heard these words, the entire scope of the Creator God’s plan of salvation (exodus) was brought into the picture. This plan did not begin with Jesus, but rather, with Adam.