This world is my home
Sometime in the early 20th century, American Christians forgot the importance of the earth.
The reasons are complex, but they boil down to a pessimistic view of the future and a vaguely Gnostic distrust of the physical. This view led not only to prohibitions on good things like alcohol, but also to an overemphasis of the spiritual and Heaven versus the physical and Earth.
In a recent sermon (PDF), Doug Wilson encapsulated why Christians should care about creating a good city:
Many Christians believe the cosmos has an upper and lower story, with earth as the lower and heaven as the upper. You live the first chapters of your life here. Then you die, and you move upstairs to live with the nice people in part two. There might be some kind of sequel after that, but it is all kind of hazy. The basic movement in this thinking is from Philippi “below” to Rome “above.”
But what Paul teaches us here is quite different. We are establishing the colonies of heaven here, now. When we die, we get the privilege of visiting the heavenly motherland, which is quite different than moving there permanently. After this brief visit, the Lord will bring us all back here for the final and great transformation of the colonists (and the colonies). In short, our time in heaven is the intermediate state. It is not the case that our time here is the intermediate state. There is an old folk song that says, “This world is not my home, I’m just passing through.” This captures the mistake almost perfectly. But as the saints gather in heaven, which is the real intermediate state, the growing question is, “When do we get to go back home?” And so this means that heaven is the place that we are just “passing through.”
Or as Paul Marshall puts it: “Heaven Is Not My Home.”