In the book of Revelation, a contrast is made between God’s people and “those who live on earth.” In Letters From The Lamb I wrote:
Since the Philadelphians have been faithful, Jesus says that he is going to protect them from a time of trial that is coming on those that live on the earth. While at first glance we might think that all of us “live on the earth,” a survey of Revelation will show us that a distinction is made between those that dwell on the earth and those that dwell in heaven. The first term refers to the worldly people, those that reject God and follow the rebellious worship of the emperor. Those who dwell in heaven, on the other hand, are the citizens of heaven, even those that are still living their lives on this planet. They are in the world, but not of the world. Their passports and driver’s licenses may state an address here, but their actual citizenship is in heaven. So when Jesus brings punishment on those that live on the earth, his people are not included in that punishment.
(Letters From The Lamb, p. 138)
We are part of a kingdom that isn’t of this earth. Our loyalties lie elsewhere. We seek a heavenly city, not the country that we were born in. Living as aliens on this earth is an important part of our identity as Christians.