Questions about the influence of Christianity on American politics and policies are front and centre because of the forthcoming election. So a hard look at a controversial subject is particularly welcome just now, and an academic criminologist has provided one.

Elicka Peterson Sparks is an associate professor at the Department of Government and Justice Studies at Appalachian State University in Boone, North Carolina. In her book The Devil You Know: the Surprising Link Between Conservative Christianity and Crime, she argues that it's the Christian Right, or more particularly 'Christian nationalists', that actually cause crime and promote violence.

One of the problems she highlights is that fundamentalists uncritically use parts of the Bible that are "rife with violence, particularly violent retribution".

She writes: "When viewed as the literal word of God, this conveys God's blessing on the use of violence in the fact of opposition to anything perceived as being God's will."

Full disclosure: I haven't read it so won't comment on the book. But as a jumping-off point to think about fundamentalism, it's a good place to start.

The online dictionary.com says fundamentalism is "a religious movement characterised by a strict belief in the literal interpretation of religious texts, especially within American Protestantism and Islam" – a definition that would horrify both by bracketing them together. There's much more to it than that, and it's not just American Protestantism, of course – though The Fundamentals, the 12 books published in 1910 that popularised the term, were American.

The fundamental characteristic of any form of religious fundamentalism is a profound reluctance to allow anything from outside the faith to influence the reading of the text. So the fact that the overwhelming scientific consensus is that the world is billions of years old and that life arose from a process of evolution does not affect the fundamentalist's view that the first chapters of Genesis are historical. Scholarly discoveries about processes by which the first five books of the Bible came to be written don't shake their belief that Moses wrote them all.

That sort of thing doesn't matter so much. But writers like Sparks put their finger on another, more serious issue: that interpreting the Bible purely in terms of itself can lead us down some very dark paths indeed. There are plenty of places, especially in the Old Testament, where God appears to command, endorse or inflict terrible violence on his enemies. One example is the story of Noah's Ark, when an entire population is destroyed. Another is the massacres inflicted by the victorious armies of Joshua during the conquest of Canaan. No one can read Psalm 137:9, "Happy is the one who seizes your infants and dashes them against the rocks", without wondering what's going on.

The question is, how do you deal with these stories? It's possible to say, "They're in the Bible so it must be right to treat God's enemies like that." Certainly the New Testament seems to take a less bloodthirsty line, generally speaking, but real fundamentalists reject any idea of theological development through the Scriptures: what matters is the text, and Old and New Testaments are both the Word of God.

So it's possible to use the Bible as a textbook in a most unhelpful way. I recall a sermon at the church where I grew up where the preacher argued for the death penalty on the grounds that the Bible says "the magistrate does not bear the sword in vain" (Romans 13:4). Attitudes toward crime and criminals shaped purely by the text of the Scriptures are not likely to be very enlightened.

Furthermore, enemies can be given a religious label and treated with extreme violence. Ted Cruz, for instance, one of the leading contenders for the Republican nomination, has promised to "carpet bomb [ISIS] into oblivion", adding: "I don't know if sand can glow in the dark, but we're going to find out." Any thought that there are real people under the rain of bombs he intends to unleash – or even that the terrain of Iraq and Syria might comprise more than sand – is entirely lacking.

Another example is slavery, which is condoned throughout the Bible. It's fair enough to point out the differences between biblical slavery – which was regulated and as humane as such institutions can be – and the transatlantic trade, which was the precise reverse – but the point is that the one could be credibly used to justify the other (attempts to claim Wilberforce as a great Christian hero need to be set alongside the fact that his opponents were Christians too). It took the Enlightenment to win that argument, not just more Bible reading.

What fundamentalists don't get is that new situations and new ideas ask new questions of the Bible – and new answers emerge. We don't have to believe in the death penalty just because the Old Testament assumes it's OK. We don't have to believe that wholesale massacres are right for the same reason. The value and the truth of the Bible isn't compromised by that. Instead, it amazes us by still speaking into our world two or three thousand years after it was written.

In his short story The Sign of the Broken Sword, GK Chesterton writes of a great general who reads far too much in the Old Testament and is led to commit a terrible crime. "St Clare was an old Anglo-Indian Protestant soldier," says Father Brown. "Now just think what that might mean... It might mean a man physically formidable living under a tropic sun in an Oriental society, and soaking himself without sense or guidance in an Oriental book. Of course he read the Old Testament rather than the New. Of course he found in the Old Testament anything that he wanted – lust, tyranny, treason... In each of the hot and secret countries to which that man went he kept a harem, he tortured witnesses, he amassed shameful gold; but certainly he would have said with steady eyes that he did it to the glory of the Lord."

He sums it up: "When will people understand that it is useless for a man to read the Bible unless he also reads everyone else's Bible?"

The cure for fundamentalism is just that: reading other people's Bibles, being prepared to learn from science, psychology, philosophy and even from other faiths as well as from our own Scriptures. Unless we do, we'll find ourselves at best ignoring the voice of God speaking "beyond the sacred page", and at worst committing serious sin.

Follow Mark Woods on Twitter: @RevMarkWoods