Bring back Nicola Sturgeon. The race to replace her as SNP leader and first minister has turned into the mother of all culture wars. Who would have thought that the party of independence would start tearing itself apart over a law on same sex marriage that was passed nearly a decade ago?

The early front runner, Kate Forbes, provoked fury among ‘progressive’ SNP supporters on Twitter by saying she opposes gay marriage – something everyone who knows her knew perfectly well. She is an evangelical Christian for heaven’s sake, a member of the Free Church of Scotland. Of course she opposes gay marriage. That along with having children out of wedlock and working on the sabbath.

However, the Scottish finance secretary, who is still on maternity leave, went on to insist that these are her personal views, not her political ones. Forbes compared herself to former German chancellor Angela Merkel, who opposed same sex marriage but accepted the democratic decision to introduce it.

The truth is that none of the SNP leadership rivals looks a fitting successor to Sturgeon

But that didn’t satisfy a number of Forbes’s erstwhile supporters, including the just transition minister, Richard Lochhead. He withdrew his support on the grounds that her views on marriage are incompatible with leadership in the modern age. Others came straight out with it and branded her a ‘right wing bigot’.

Equal marriage is, of course, a cypher for the real issue tearing the SNP apart: the Gender Recognition Reform Bill. Forbes has effectively said she will scrap Sturgeon’s legislation to allow 16-year-olds to change their legal sex by declaration. At any rate, she will not challenge the UK government’s decision to block it under Section 35 of the Scotland Act. Westminster’s Scottish Secretary, Alister Jack, did so on the grounds that it would conflict with protections for women and girls under the UK-wide Equality Act. The row about male-bodied sex offenders being placed in women’s prisons suggests it very well might. But the SNP’s coalition partners, the Greens, say they will ‘walk’ if the GRR Bill is abandoned or changed.

Forbes’s main rival, health secretary Humza Yousaf, has insisted that he still supports the Bill ‘100 per cent’.  As the Sturgeon continuity candidate, he says he would fight what he calls the UK government’s ‘attack on devolution’ all the way to the Supreme Court. He also says he supports same sex marriage, even though it is against his Muslim faith. Indeed, the Quran and other Muslim texts are as hostile toward homosexuality as the Bible. Nor did Yousaf vote for the 2014 Equal Marriage Act. He had a diplomatic absence on the day of the vote – although he did support the bill in principle at an early stage.

The third candidate so far, former community safety minister Ash Regan, says she too would scrap the GRR Bill. She also wants to protect the North Sea oil and gas industry, even if that means slowing progress to net zero. But she does support same sex marriage, for what it’s worth. It’s not clear how much support Regan has in the SNP. She has much less ministerial experience than her rivals and little public profile. Her main claim to fame is that she resigned over the GRR Bill last year.

But perhaps a little too much is known about Yousaf’s ministerial experience; it’s mainly experience of failure, according to his critics. He was transport minister when the disastrous island Ferry contracts were going south and when there was a public outcry about the state of the rail service – or ‘Scotfail’ as it was named. As justice secretary, he was responsible for the illiberal Hate Crime Act which outlaws ‘stirring up hatred’, even in the privacy of someone’s home.

Since he took charge of health, the NHS has ceased to function in large parts of Scotland according to Dr Iain Kennedy, chair of the British Medical Association. Waiting times are at historic levels, dentistry is being effectively privatised – and it takes the most dedicated patient to secure a GP appointment. Labour is hoping against hope that Yousaf wins, because they believe he is a three-time ministerial loser.

But the truth is that none of the SNP leadership rivals looks a fitting successor to Sturgeon. There is precious little vision so far on the real issues: the economy, health and education. The race has been dominated by Twitter, which is why it appears to be solely about gender and same-sex marriage.

We often talk loosely of culture wars in the context of jokes, pronouns and microaggressions. But there is a genuine culture war taking place now in Scotland. It will be fascinating to learn just how many in the SNP agree that Kate Forbes should be excluded from political office because she is a Christian who truly believes in her faith. The 100,000-strong congregation of the SNP will give their verdict in six weeks’ time.