If you’re looking for a snapshot of the state of global Christianity today, a good place to start would be by looking at two violently contrasting Sarahs: Bishop Sarah, and Cardinal Sarah. One is Anglican, the other Catholic; one white, the other black; one bland, the other terrifying. Both are tipped to be leaders of their respective churches: Bishop Sarah as a future archbishop of Canterbury; Cardinal Sarah as a possible pope. I wonder which of them Jesus would prefer to be stuck on a desert island with.

Sarah Mullally, the Bishop of London–elect, comes across as about the most upbeat, smiley person you could hope to meet. A happily married, down-to-earth ex-nurse and mother of two, Bishop Sarah wants everyone in the world to be kind and happy and to feel loved by her and to love her. She knows London has a reputation as a polarised diocese full of misogynistic clergy who refuse to be ordained by a woman, and she wants to spread the love and make everyone as nice and accepting as she is. Slightly nervous of her own voice, she’s a retweeter rather than a tweeter, and she only retweets soothing things, such as ‘#TacklingHomelessnessTogether’ and ‘Plant a seed today — in your garden, in a relationship or amongst the pains of the world’. She uses Fairtrade products wherever possible.

Her statements are so well-meaning and wishy-washy that you can neither argue with nor remember them. When obliged to write something on her new appointment, she said: ‘Churches confident in faith, compassionate in action and creative in partnership come about when local ministers are supported to be the best they can and members of their congregations are encouraged to flourish and be ambassadors for their faith.’

She’s really nice and supportive to gay people but can’t go as far as actually saying that they should be allowed church blessings, because that is not yet the party line.

With her background as Chief Nursing Officer, she is the perfect fit for today’s new breed of not-too-intellectual Anglican bishops with experience in the secular world. Justin Welby (who’s becoming increasingly autocratic in the matter of senior appointments) clearly didn’t care that she’d only been a suffragan bishop for two years. He wanted to be seen to appoint a woman — this woman, admirable champion of ‘patient experience’ in the NHS — and he fast-tracked her to stardom. It remains to be seen to what extent she is out of her depth when it comes to preaching memorable sermons at royal funerals.

She’s currently chairing the committee preparing a ‘teaching document’ about human sexuality to be released in 2020, and modernisers are hoping that she’ll bring her medical and biological knowledge to bear on the debate.

Cardinal Sarah — Cardinal Robert Sarah — is so different that it’s hard to believe both Sarahs emerged from having read the same gospel. Born in 1945 in Guinea, West Africa, and now a member of the Roman Curia, Cardinal Sarah has no fear of speaking out and couldn’t care less who hates him. As far as he’s concerned, it’s the Catholic church’s job to be the ultra-strict headmaster of the depraved modern world, the immovable rock against which rule-breaking secularism bangs its head. He’s one of the cardinals who can’t bear Pope Francis’s gently modernising trends.

Far from being upbeat, Cardinal Sarah believes the West is ‘committing suicide’ (as he put it last month) by allowing tolerance of ‘evil’ habits and thereby abandoning God. From his position of priestly celibacy, he pronounces obsessively on the fundamental importance of the family, and by ‘family’ he means one man married to one woman for life: no cohabitation, separation, divorce or remarriage ever. ‘Gender ideology and Isis,’ he says, are ‘the two radicalisations’ that threaten the family, and by ‘gender ideology’ he means divorce, same-sex union and abortion.

His sayings are certainly more memorable than Bishop Sarah’s. Standing at lecterns looking splendid in his cardinal’s robes, he says things like, ‘The rupture of the foundational relationships of someone’s life — through separation or divorce or cohabitation or same-sex unions — is a deep wound that closes the hearts to self-giving love and leads to cynicism and despair.’ He cites the Devil, Lucifer, Satan and Belial, all variations on the name of the Evil One responsible for these developments.

Whatever it is, basically, if it’s modern and makes life easy for anyone, he’s agin it. Even in the matter of whether Holy Communion should be taken kneeling and on the tongue or standing and in the hand, Cardinal Sarah sees a war between Michael and his angels on one side and Lucifer on the other. Communion in the hand, he says, involves a great dispersion of fragments of the host in the form of tiny wafer crumbs — and these crumbs are the body of the Lord. The crumb-spilling is therefore an outrage against the Blessed Sacrament and a tool in the hand of Satan.

When a Pope and an Archbishop of Canterbury kneel down together, as they sometimes do, and we all think, ‘How nice — maybe the two churches will get back together one day’, it’s salutary to think of the two Sarahs and be reminded just how far apart the two churches still are, at their extremes. African Anglican bishops are still resolutely anti-gay and anti-women priests, making things hard enough to nudge along in the Anglican church; but Cardinal Sarah takes rigidity to a new level.

He does have gravitas, though — something I can’t help thinking Bishop Sarah rather lacks. The theological training must be something to do with it. Whereas Bishop Sarah did an evening or two a week at the South East Institute for Theological Education, starting at the age of 36 and still holding down her job as a nurse, Cardinal Sarah was sent off to the Saint Augustine Minor Seminary in the Ivory Coast at the age of 12, from where he proceeded to the Grand Seminary in Nancy, France, and then to five years at the Pontifical Gregorian University, where he obtained a licentiate in theology in the days when lectures were still in Latin.

Bishop Sarah claims to enjoy reading theology, and she has a special soft spot for the writings of Desmond Tutu, but she can’t have Cardinal Sarah’s depth of theological knowledge. And some would say, ‘Damn good thing’, if the knowledge drummed into a boy through years in seminaries leads to such frightening religious right-wingery.

The remarriage of the two divorced churches is as unlikely to happen any time soon as the remarriage of a divorced couple in a church in Cardinal Sarah’s home diocese of Conakry, Guinea.