C.S. Lewis would have been appalled by modern contemplations of heaven found in Christian bookstores. Some see John’s measure in the end of Revelation, and assume that the author is interested in conveying an exact dimension. Liberals on the other hand despise and mock any version of heaven since the literal descriptions thereof have more in common with fairy tales than an actual place. Though these perspectives may be slightly different, they all suffer from one similar problem–literalism.
No Biblical thinker will deny the legitimacy of a real heaven, where real people will walk in real places. However, the danger in interpretation is that genres are often overlooked. Take for example, the apocalyptic dimensions of the Revelation of Jesus Christ. Anyone familiar with such language will immediately assume that it is rarely if ever used literally.
According to Lewis, we cannot understand these to be literal but symbolic. To assume that these descriptions were literal betrays a fundamental principle of Hermeneutic. The early fathers understood such and so did the Reformers. Lewis has a few words for those who attempt to make the text the unthinkable:
People who take these symbols literally might as well think that when Christ told us to be like doves, He meant that we were to lay eggs.
 Revelation 21:15-21
 Consider the usage of numbers such as 144,000 in Revelation 7.
 Mere Christianity, pg. 123.