Is nationalism a sin?

A few weeks ago I read a recently published book by David Martin entitled "Different: Our witness and the sins that work against it" (see below). The author devotes one chapter to each of four sins:

  1. Materialism: Caravans and the Exodus
  2. Careerism: Reputations and Sandcastles
  3. Sentimentalism: Old Age, Old Adage, Old Advantage
  4. Nationalism: Borders and Belief

Interesting stuff. But is nationalism a sin? It isn't something that I have often heard called out as such in evangelical circles.

The Apostle Paul despised neither his Roman citizenship nor his Jewishness and nor should we despise our own nationality. Indeed Paul used both of these aspects of his personality to promote the gospel. But he didn't overdo it either: he didn't campaign to "Make Rome Great Again".

The Christian truly belongs neither to this world, nor to its institutions, nor to its nations. Christians are not of this world, but sent into it.

"So then you are no longer strangers and aliens, but you are fellow citizens with the saints and members of the household of God." Ephesians 2:19 (ESV)

"But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light... I urge you as sojourners and exiles..." 1 Peter 2:9 & 11 (ESV).

For the most common meanings of the word "nationalism", it is indeed a sin to harbour such sentiments.