Without wishing to get bogged down in a complex debate about free will, I'm not sure I can avoid developing a bit of a crush on the Archbishop of Canterbury. I am grateful to both the Martins for their input on this one: Martin Luther of Wittenberg for suggesting that there's basically nothing I can do about it because it's all predetermined. And Martin Lewis of MoneySavingExpert.com for once calculating that £100 borrowed at Wonga's APR would, within seven years, exceed the US national debt.

It is undeniably unfortunate that Justin Welby's vow to use credit unions to compete payday loan firms out of business should have enjoyed admiring headlines for approximately 27 minutes this week, before it was revealed that the Church of England holds an indirect stake in Wonga via its pension fund. But for my godless money, the archbish made the most disarmingly engaging of Today programme interviewees this morning when asked about the contradiction. He was dreadfully embarrassed, he admitted to John Humphrys. About eight, on a scale of one to 10. He has called for a review of church investment guidelines, after which the £75,000 will doubtless be withdrawn.

The terms of the most high-profile payday loan outfit are not a two-way street, of course, which is a shame for the C of E, because if it was entitled to the firm's standard APR when clawing back its £75,000 investment, it would presumably now be worth more than all the money on the whole planet for ever and ever. The Vatican would look like church mice.

As for the contradictions of the church's investment, I imagine I'd be laughed out of Sunday school for claiming that the dense theological argument shakes down to whether a little bit of hypocrisy is worse than a lot of what the payday lenders do. For the righteous atheists of the internet commenter circuit, it apparently is. Hurrah for such arbiters – as no one wondering how on earth they are going to feed their kids with a metastasising monthly repayment hanging over them is probably saying.

Indeed, if an indirectly invested £75,000 out of £5.5bn is all it is going to take for people to tell the church to do one on this issue, then the darker forces of capitalism must also be thrilled. Talk about cheap at the price. The people actually caught up in the desperate, cyclical clutches of such loans probably don't give quite so much of a toss about absolute ethical consistency in the pension fund arrangements of the single major institution that has unveiled any sort of plan for countering them. Still, what do they matter?

Not a lot, if the failure of any of the main party leaders to propose an interest rate cap is anything to go by. The BBC's Paul Lewis investigated the idea back in 2004 – "when we thought 170% was high!" – and concluded that "the further you get from real people borrowing at high rates the less you support an interest rate cap". By his own testament, Welby has lived among deprived communities where many of the customers of what Martin Lewis calls "this dirty business" are from. He has had staff caught up in it.

Mostly, though, Welby appears something of a mould-breaker, which is perhaps why the bishop who once declined to ordain him opined, "There is no place for you in the Church of England". He's certainly a mould-breaker in modern British public life, where we are now wholly unused to the ruling classes having had a job outside of that public life. Welby's oil business background may not be everyone's cup of tea, but it somehow feels more of a preparation for the world than that undertaken by any of the main party leaders.

It also gives him the air of that most historically admired of British types, the gentleman amateur. He came late to the church game – describing his moment of conversion as something that embarrassed him, "like getting measles" – and his meteoric rise does not appear, at least to lay folk, to be the result of his politicking his way up the greasy pole.

He's not going to make me a believer or anything, but it does feel encouraging to have such a person leading an institution whose absolute insistence on ineffectuality has been its defining characteristic for decades. Giles Fraser, the former canon chancellor of St Paul's Cathedral, was the last person to attempt to make the church relevant, when he resigned in 2011 over the cathedral's vow to evict the anti-capitalist protesters from its steps.

That action was swiftly slapped down in an article by Welby's more intellectually challenged predecessor George Carey, in which the latter alighted tone-deafly on the language of commerce to make his point, whingeing that the protesters had "put [St Paul's] out of business for a week". Small wonder that so many people's view of the church's relations with mammon has been gleaned from the sacred text of Blackadder, where the baby-eating bishop of Bath and Wells is also the assistant manager of the Bank of the Black Monks of St Herod. Motto: "Banking with a smile and a stab".

So bravo to Welby for at least having the other sort of stab. And if he's short of stunts to take the campaign forward, might I suggest he signs up Martin Lewis, who could nail his 95 theses to the payday lenders' doors.

Twitter: @MarinaHyde