It is a commonplace with preachers to point out that as Christians we have two addresses, two places of residence. This dual citizenship is expressed frequently, and in varied ways, throughout Scripture.
In writing to the Corinthians, for example, the apostle Paul greets ‘the church or God in Corinth…those sanctified in Christ Jesus’ (1 Cor 1:1). They are ‘in Corinth’, and they are at the same time ‘in Christ’. The same apostle writes to ‘all the saints in Christ Jesus at Philippi’ (Phil 1:1), and later in that same letter makes it clear where our primary home is: ‘our citizenship is in heaven’ (Phil 3:20).
The letter to the Hebrews presents the contrast not so much as ‘here and there’ but as ‘present and future’: ‘Here we do not have an enduring city, but we are looking for the city that is to come (Heb 13:14).
The book of Daniel (see especially Daniel 1) is very much a tale of two cities. Daniel and his three young friends have been hauled off to Babylon. The question is, whether they become so immersed in all that Babylon stands for that they will forget all that Jerusalem stands for. So powerful is this image that it is picked up again in the last book of the Bible. Babylon (representing all that is godless and unholy) is destroyed (Rev 18), whereas Jerusalem (the city of God) ‘comes down out of heaven from God’, to be the place where God dwells with his people for ever (Rev 21:1-4).
Christian teachers often quote the slogan, based on our Lord’s prayer in Jn 17 – ‘in the world, but not of the world’. This does not quite do justice to what Jesus actually prayed, for he added: ‘As you sent me into the world, I have sent them into the world’ (Jn 17:18). (See this article). We have been sent, as Jesus declared elsewhere, to be ‘the salt of the earth’ and ‘the light of the world’ (Mt 5:13f).
We live in a world which is good and beautiful in many ways. But it is ‘an inn, a tent, a lodging, a training school’ (Ryle). But it is not our permanent home. Like Abraham of old, we ‘live in tents’ so far as this world is concerned, knowing that our permanent home is ‘the city with foundations, whose architect and builder is God’ (Heb 11:10).