I found it pretty profound when I first heard it, but stupid me, never wrote it down. Now I need to find it, so I turn to the Teeming Millions. I’ve looked at many CS Lewis sites, but I haven’t found it, so it may not be his.
It goes a little something like this:
I believe when you die, you become more of what you were in real life.
or
I believe when you die, you become what you were during life, only more so.
or
I don’t believe in heaven. When you die you become what you were in life, only more so.
Nothing like that is listed on the C.S. Lewis Quote Page; but the quotes on that page are by no means exhaustive. There is only one quote from The Great Divorce, for example.
Lewis, in GD and elsewhere, described heaven as a place that is “more real” than earth. In fact, earth is described as “shadowlands,” a poor, barely real reflection of heaven. This is also the theme of the last few chapters of The Last Battle from the Chronicles of Narnia.
That said, I can’t find any quote that suggests that people become more real, or more themselves, in the afterlife. I agree that it doesn’t sound like him.