Christians need to develop a "deeper ecology" that integrates prayer and social activism, according to the founder of the 24/7 prayer movement.
Speaking at the Books for Life Live event at Trinity Church in Cheltenham, Pete Greig said: "At every level, prayer and social engagement belong together. Jesus sets no other precedent."
He said Jesus was profoundly prayerful, but stated his mission as being to preach "good news to the poor". It was vital to integrate the two, said Greig; deep prayerfulness that omitted action for others failed in this, but so did those who spend their lives "frantically fighting injustice" without a commitment to prayer.
He instanced Mother Teresa, whose order rescues and cares for dying people. "If you're thinking strategically rather than prayerfully, it's the least strategic thing you could do with your time because they will all die," he said. However, for Mother Teresa's order it was "an act of devotion to Christ": "There's something about being rooted in the heart and purpose of God that enables us to live meaningfully and sustainably in the world."
Greig also spoke of his book Dirty Glory (Hodder, £13.99). "It's about the paradox of grace," he said. "It seems to me that God's story is about His glory getting dirty, with messed-up people like ourselves carrying his glory into very dark places.
"My conviction is that God's glory belongs with us in the dirt."
He spoke of the birth of Jesus as "the glory of God lying incontinent and inarticulate in the manger".
Greig also spoke movingly of the illness of his wife Sammy and the times of testing they have faced together. After the rapid growth of the 24/7 prayer movement, he said, "for a while, we thought, this is it, we've found the great revival switch; everyone's doing it. Then my wife got sick and very nearly died many times. I thought these prayers could save world, and now I wasn't sure they could save my wife."
However, he said: "We mustn't misunderstand God's silence for his absence."
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