Bill Johnson, senior pastor at Bethel Church in Redding, California, sent shockwaves through the charismatic Christian world when he announced on Facebook he had voted for Donald Trump.

He was not alone. Dozens of other well known Christian leaders announced their endorsement of the Republican, to the confusion of other religious figures across the world.

Jerry Falwell Jr, Wayne Grudem, Robert Jeffress, James Dobson and Franklin Graham were among a long list of evangelical leaders to either explicitly or implicitly back the New York billionaire.

Although Grudem wavered when a video emerged in which Trump boasted of sexually harassing women, his support remained loyal.

For many evangelicals, the alternative was too horrific to consider.

Hillary Clinton not only embodied the liberal Washington establishment but more crucially for conservative evangelicals she was also the icon of the pro-choice, abortion-on-demand sentiment they so despised.

"I found that murder/abortion was wrong, which Clinton approves of even up to the point of delivery," Johnson wrote in his defence of voting Trump. "Changing the name from baby to fetus doesn't change reality. It's a baby. A woman has a right to decide what happens to her own body. But all of our rights stop when they violate the rights of another – in this case the unborn."

Trump guaranteed he would pack the US Supreme Court with conservative judges giving right-wing Christians more assurance in upcoming battles over gay and transgender rights.

So they turned a blind eye to Trump's multiple divorces and erratic temperament.

"They saw very deep values threatened by the Clintons," says Conrad Gempf, an American New Testament theologian and lecturer at the London School of Theology.

In an interview with Christian Today, he explained why a man who horrified many Christian leaders in the UK and Europe gained such strong and faithful support from evangelicals in the US.

"If you grant that legislation should be a description of Christian morality then you have a very hard time endorsing Clinton, who is going to push legislation that is more open, than you do with Trump who doesn't know what he is talking about and won't push anything," Gemf said.

An open supporter of Obama, Gempf added: "The problem is I don't think they have thought it through carefully enough.

"I think there is a problem with Christians trying to legislate morality. If you believe a certain kind of sexual behaviour is wrong, someone who is not a Christian has no way of knowing that at this point. So the most you can say is 'trust me it's wrong because I know'.

"That just isn't good enough grounds for dictating their behaviour."

Gemf added that democracy and legislation was a rigid and difficult thing to work into morality.

"If you had a referendum on homosexuality – should homosexuality be allowed or not – the Christian might answer one way if they're being asked 'do you think this behaviour is good'.

"And they might answer another way if they're being asked 'do you think this something we should enforce on everyone and punish them if they don't agree'.

"And it is difficult to know what the government is asking. Is it asking what would be ideal behaviour or is the government asking something else?

"Until you think about it really deeply I can see how you can come out and say there is no way I can support Clinton."