Jerry Falwell Jr seems confused. The head of Liberty University is one of Donald Trump's most vocal and significant evangelical supporters. His father Jerry Falwell was one of the most significant leaders of the Religious Right, the founder of the Moral Majority and one of the key players in the transformation of the evangelical vote into a solid Republican bloc.

Jerry Jr had seemed set to continue his father's legacy, especially after replacing his late dad as Chancellor of Liberty – one of the world's most prominent evangelical educational institutions.

So is Falwell Jr, like his father, a proponent of the Religious Right, which wants to win political power and install evangelical values into Washington DC? Or does he actually think politics isn't something Christians shouldn't be involved in?

While being interviewed by CNN about his support for Trump, the younger Falwell said, "Jesus never intended to give instructions to political leaders on how to run a country. That's clear through all his teachings – he made that more clear than almost anything else."

When asked about the refugee crisis, Falwell added, "When Jesus said 'turn the other cheek' he didn't mean that instruction for Roman soldiers who happened to be Christian. You step into a different role when you become a citizen, when you become a president of a country, when you become a Roman Emperor. So Jesus said leave those things to the political elite, let them make those decisions. Jesus taught personal charity, he taught us how we treat each other, to love our neighbour as ourselves, in our personal relationships."

It seems that Falwell Jr has become the latest figure to fall into a trap which has ensnared countless Christians since the Reformation and the Enlightenment. Falwell's view of the gospel is personal but not corporate. "You step into a different role when you become a citizen," he says. Really? I can't find that anywhere in my Bible. This distinction between Christian private life and secular citizen is a distinctly modern invention.

In the clip, Falwell shows a lack of understanding about the context into which Jesus spoke. He draws a distinction between the 'religious leaders' Jesus criticised and the 'political leaders' of the day – the Romans. This would be odd to a First Century Jew. Yes, the Romans were in control politically, but the Jewish religious elite was also a political elite. The Chief Priest and his court had political power in that world.

Falwell is reading back into Jesus' time a division between religion and politics which is a thoroughly modern innovation. When the founders and framers separated the US Church and State (in a way that has never been the case in the UK) they were influenced by the political theorists of their day. John Locke and Thomas Paine were the intellectual powerhouses behind the separation of Church and State – not the Bible.

That Falwell's Jesus is only interested in our personal lives is unsurprising. Falwell isn't a theologian – and is steeped in a peculiarly American, individualist faith. American evangelicalism is a product of the Protestant Reformation which wrested back a requirement for personal relationship between an individual and God – rather than a person being reliant on priest or other intermediary for salvation.

This vital corrective of Protestantism has been accentuated beyond caricature in Falwell's words. He implies that as long as we treat our neighbours well and have our own relationship with God, then politics isn't our domain. In support of this, Falwell suggests Jesus' famous saying, "Render therefore unto Caesar the things which are Caesar's, and unto God the things that are God's."

Individualist Christians say this proves Jesus wasn't interested in temporal political structures at all. But this is a crass misreading of Jesus. NT Wright explodes this individualism as a myth. "It is not an isolated 'political' comment in an otherwise nonpolitical sequence of thought," he says.

Wright suggests Jesus is very definitely not advocating a complete divide between faith and politics. "Jesus did not mean it as indicating a separation between the spheres of Caesar and God, with each taking responsibility for a distinct part of the world... Of course, Jesus acknowledges, you may have to pay taxes to the pagans, just as Jews in exile had to pray to God for the welfare of Babylon; but that doesn't mean that God is only concerned with a different, 'spiritual' world. God is present in the ambiguity, summoning people to an allegiance which transcended but certainly included the position they found themselves in vis-a-vis the occupying power."

NT Wright is drawing on the tradition of St Augustine. While some individualists have suggested that Augustine's City of God actually supports an ironclad separation of Church and State, that isn't the case. As Peter Rozic says, "While Augustine's doctrine of the two cities does defend the glorious city of God against the pagan city of humanity, it also invites the reader of De Civitate Dei to find genuine references common to the two cities. Moreover, Augustine's use of the two-cities doctrine does not restrict a Christian to a passive obedience of any regime whatsoever. Despite Augustine's emphasis on both the primacy of God's action and the sinfulness of humanity, he calls for an active Christian involvement in political life and thus for a nonexclusionary church-state relationship."

This nuanced position gets us beyond simplistic claims that 'Jesus is only interested in our personal lives' or 'Jesus only wants us to do charity, not government.' Actually, the Bible and Church teaching have an awful lot to say about how society should be structured. From Calvinists to Catholics there are solid theological bases for speaking about how politics should work, not just our personal lives.

Protestant theologian and Prime Minister of The Netherlands Abraham Kuyper famously declared, "There is not a square inch in the whole domain of our human existence over which Christ, who is Sovereign over all, does not cry: 'Mine!'" This doesn't mean Kuyper set out a specific political programme which all Christians must follow; but the idea that Christians shouldn't seek to be involved in politics at all was anathema to him. (Ironically, Kuyper's own theology was taken to extreme lengths via RJ Rushdoony and the Christian Reconstructionist movement which inspired Falwell Sr's Religious Right.)

From a Roman Catholic standpoint, since 1891 the whole area of Catholic Social Thought has been expounded and extended to give a strong set of guidelines as to how society should be organised, in terms of property rights, just wages and more – again, without going so far as to recommend specific policies.

Why then should we care what Falwell says?

For two reasons... Firstly, if Falwell is seeking cover for his endorsement of Trump, this is a bad idea. Trump's policies need to be critiqued from our perspective as Christians, rather than just as secular citizens. His ideas are radical and before voting for him, Christians will want to interrogate his positions.

Secondly, we miss out on the gospel's transforming power if we limit its sphere of influence to merely our 'personal lives.' The radical good news of Jesus isn't just for us personally, it's for the whole of the created order. That doesn't mean a theocracy (at least not that kind of theocracy). It does, however, mean a place for our faith in politics, in government and in the public square. It also means politicians should be held to a high standard. Something Falwell would do well to remind Trump – and the rest of the Republican and Democratic candidates – of.