Why does Mike Pence continue to serve a President who mocks his beliefs?

The revelation that President Donald Trump mocks the religious beliefs of his vice-president Mike Pence shouldn't really have surprised anyone.

In a far from flattering profile of Pence in the New Yorker, reporter Jane Mayer recounts how Trump would ask people who saw him after stopping by Pence's office, 'Did Mike make you pray?' He also needled Pence on his views about abortion and homosexuality, once gesturing to Pence when the conversation turned to gay rights and saying, 'Don't ask that guy - he wants to hang them all!'

President Donald Trump (R), and Vice President Mike Pence (L)

Pence's views on these issues are well documented. As an evangelical from a Catholic background, he is vehemently opposed to abortion and homosexuality. As Mayer says: 'He was as far right as you could go without falling off the earth,' Mike Lofgren, a former Republican congressional staff member, who has become a Trump critic, told me.'

However, she adds: 'But he never really put a foot wrong politically. Beneath the Bible-thumping earnestness was a calculating and ambitious pol.'

There's nothing wrong in principle with calculation and ambition. These are necessary skills in an effective politician. Where the difficulty lies, however, is in the lack of respect Trump shows to his deputy's religious beliefs – and by extension, to Pence himself. How can the evangelical Mike Pence continue to serve a president whose personal beliefs and character are so wildly at variance with his own?

These revelations are unflattering to Pence. But any suggestion that he is fatally compromised by Trump's treatment of him misunderstands two things. First, he was not appointed by the president, but elected by the people. There's an important difference. While many of those around Trump are motivated by a public service ethic that means they will tolerate behaviour they wouldn't put up with in the private sphere, Pence is directly obligated to the public for his job. He may well feel he has to make it work for that reason.

But as an evangelical in public service, he is also part of a grand devil's bargain with the president. One of Trump's evangelical supporters during the election campaign was Wayne Grudem, who made it clear that while he objected to some of Trump's behaviour, he agreed with most of his policies: 'My conclusion is that the most likely result of voting for Trump is that he will govern for the most part in the way he promises to do, bringing good to the nation in many areas.'

This is the calculation made by most of Trump's unofficial evangelical advisory council, who have stuck by him in spite of calls for them to distance themselves from him after his disastrous handling of the Charlottesville tragedy. Their line is that they have a responsibility to try to influence him for good as far as they can. The perception that they are compromising their integrity in the process is unfortunate, but it's a price they have to pay for doing the right thing.

Pence is in a similar position, with an added twist. He is an ideological fundamentalist, whose stated positions are far to the right of the American mainstream. Furthermore, while he has not convinced everyone about his administrative capabilities, he would be a far more effective and consistent president than Trump. And furthermore still, if Trump fails to serve a full term, which is entirely possible – Pence becomes president by default.

His loyalty to Trump, in spite of Trump's denigration of his faith, is entirely consistent with the calculations other evangelicals have made. It doesn't look great, but it's worth it for the cause, and for the country.