The most common reaction to seeing Joyce Meyer's name on the speaker's bill for the HTB Leadership Conference seemed to be bemusement, with more than a hint of cynicism. The conference and its leaders – Nicky and Pippa Gumbel – have long been committed to ecumenism, and have welcomed those of all Christian flavours to speak. This year, rather aptly under the theme of unity, saw Archbishop of Canterbury Justin Welby and Archbishop of Westminster Vincent Nichols share the stage, while preacher to the Papal Household Father Raniero Cantalamessa and evangelist Robert Madu each gave talks. It was, by all accounts, an eclectic mix.

But Joyce Meyer? That was seen by many as a step too far. Her invitation was met with curiosity, yes, but also with some apprehension.

Why? Well, Meyer's writing tends to stray into self-help territory (titles include Never Give Up!: Relentless Determination to Overcome Life's Challenges and Eat the Cookie...Buy the Shoes: Giving Yourself Permission to Lighten Up) and she's been regularly criticised for not having any formal theological training. The 71-year-old also earns a lot (by anyone's standards) from her ministry, and travels in a multi-million dollar private jet. In 2003, a four-part report in the St Louis Post-Dispatch detailed many of Meyer's more extravagant purchases – including a $107,000 Mercedes, a $6,300 eagle sculpture and other artwork worth thousands of dollars.

Meyer maintains that her wealth is a gift from God, and shares a 'prosperity through faith' message. "If you stay in your faith, you are going to get paid," she told an audience in 2003. "I'm living now in my reward."

However, despite reservations, it's fair to say that this week at the Leadership Conference, Joyce Meyer came, saw and (almost completely) conquered.

Of course there were a few eyebrow-raising moments. A friend of mine was flattened against the wall by an onslaught of bodyguards when passing her in the corridor. Even when she was onstage, Meyer's band of escorts were never more than a few feet away – conspicuous in their dark suits and reminiscent of a guard stationed around a President, rather than a Bible teacher.

And yet, she won her audience round. She brought her testimony – an extraordinary story of God's grace – to life, and was unashamedly and powerfully honest. As detailed in her book, Beauty for Ashes, Meyer was sexually, emotionally and physically abused by her father as a young girl, while her mother turned a blind eye. She talks about this in a very no-nonsense way, as she does about other hardships she's endured, such as her brother's suicide in 2010 – "That was the height of being ridiculous... He was an opportunity waiting to happen." Rather than wallowing in these experiences, she distills from them nuggets of life advice. So, of her father she says; "The easiest thing to do when somebody hurts you is to hate them, but God has taught me the power of forgiveness." 

Meyer left her family home as soon as she could, aged 18, but later obeyed God and bought her parents a house nearby where she could care for them, despite them never having acknowledged the abuse. Then, just over a decade ago, her father asked for her forgiveness. Explaining that she had forgiven him long ago, Meyer led him to the Lord there and then, and baptised him 10 days later. "Love is not real if we can't forgive people," she said. "God uses people; we're partners with God and he wants to work through us."

Her talks were challenging, though a little light on theology and nothing particularly new. Meyer highlighted humanity's endless search for love and unconditional acceptance, pointing to Jesus as the only one in whom we can find them. Unity is a lifestyle, not an event, she added, and Christians have a duty to "stand up and be the flavour the world needs... we have to get out in our everyday lives and actually show people Jesus."

Another friend suggested an alternative title for this article – "How to make a billion dollars by spewing out the obvious, the old, and the ideas of others" – but Meyer undeniably lives out what she preaches and laughed that it's not easy to come up with a new message for her website devotionals every day.

She was also much funnier than I'd imagined. On the subject of learning to love yourself, she said: "If you don't love you, you're in for a rough ride – everywhere you go, there you are. You can't go to the bathroom without you. The moment you wake up in the morning, there you are!" and suggested that God speaks to her first thing in the morning to stop her "from having any of my own bright ideas". She received multiple rounds of applause from her audiences in the Royal Albert Hall and the Hammersmith Apollo, and even a standing ovation from some who seemed to resonate with her honesty. There was no sign of false humility – in an interview with Nicky Gumbel on Monday, Meyer described her ministry as 'successful', and said that she suspected a lot of crticism was down to jealousy. But even then the manner of delivery came across as refreshingly matter of fact, rather than arrogant.

So I went away from the conference yesterday feeling challenged by Meyer's words, attitude and lifestyle. Somehow she made a very American, televangelised approach work for a mostly British audience, and that's no mean feat.