Some things simply do not matter once you get past a certain point. Everett Dirksen, the famed Senator from Illinois put it this way. A billion here, a billion there, and pretty soon you're talking real money. Of course it is hyperbole but not by much. Who among us can imagine what it is like to have billion dollars? We can certainly conceive of the amount and write it out with decimal precision but to imagine in our minds having it or spending it is a completely different thing.
It is not that heaven is beyond our conception -- we can conceive of it well enough by writing down what is there and what is not there. Scripture does this. No sin. No death. No pain. No tears. But we cannot imagine it. Life comes to us in bits of shining accomplishment and overwhelming failures, in life that is too brief and death which seems to be permanent, in fits of joy that are accompanied by lifetimes of pain, and in moments of happiness that too quickly give way to tears of sorrow, disappointment, and despair. We can conceive of it but it is hard to imagine what it could be like. Scripture is filled with little images that we use to compare what we see around us to what is promised. Some of them are quite nice, actually. But heaven is unimaginable. We take it only by faith.
In his book The Discarded Image, C. S. Lewis suggests that our more accurate notion of the size of the stars that appear so small in the night sky really makes little difference to us. They are so far away from us that it matters little to us what size they actually are. For thought and imagination, ten million miles and a thousand million are much the same. He is, of course, exactly right. It may help us to note the correct distance we are from the stars and how large or small they are (as opposed to the size they appear in the sky) but in our mind's eye it matters not so much. Both can be conceived (that is, we can do sums with both) and neither can be imagined.
Imagining heaven is great sport but hard to do. Whenever somebody begins by saying "Heaven is like..." you know we are in trouble. Well, yes. . . and no. Inconceivable means beyond belief. But that is precisely what we are being asked to do. To believe. To believe what we cannot imagine. The Kingdom of God comes by faith not by sight. No matter how much we try to reduce the Christian life to rules or explanations or figures or sums, it is simply beyond imagination what we routinely believe, confess, and teach. That is why the Spirit must be involved. No amount of argument or rationalization will help. Writing it out on paper like putting down the unimaginable sums may be possible but faith is not something one can write. Faith is trust. Faith comes by hearing the Word of God and the Spirit is the power both of that Word and in the heart that hears. Minds may try to conceive but the imagination of the Spirit must inform our hearts to faith in such an impossible announcement of good news. And may God do that to us anew every day!