Humanity is in danger of cutting itself off from God in pursuit of autonomy, the Archbishop of Canterbury has warned.
The Most Rev Justin Welby urged Christians to follow Jesus' call to be revolutionaries without weapons in order "to change this bitter, dark world."
Preaching at St Aldates Oxford, a leading evangelical church, he said the challenges to Christian faith have not changed much in the last 300 years but opposition to the faith was growing. "Let's be under no illusions - those in the corner against Christian faith having relevance to the 21st century seem to be increasing in number and conviction."
Such opposition included those who questioned whether the Christian faith could really be held by 21st century men and women who are committed to rigorous scientific and rational thinking.
Archbishop Welby said he was totally persuaded of the Resurrection of Christ "as a historical fact".
He said any serious look at the evidence was convincing. "Christianity is completely credible as a faith. It is true, but far more than that, it is centred on loving the living Jesus who is truth itself."
To equate the Christian faith with power and prestige, with influence and investment, was to miss the point completely, he added.
"Jesus Christ was not one who got on well with the people of power. He was not an easy person to have to supper if you were in a position of influence."
Instead, Jesus was and still is with people on the margins.
"If you ask me about the primary place I see the relevance of faith for the 21st century I would take you not first to the House of Lords, or the great cathedrals, wonderful places as they are. I would take you to the room where I sat with women who had been trafficked for the sex trade yet who had found in the love of Christ one who had come to them, the weary and heavy laden, in the lives of a group of volunteers who had embodied his life and commitment.
"I would take you to the young offenders' institute where I met young men who had found forgiveness and peace from this Jesus whose love and redemption of their lives had changed everything. More than that they found truth itself, living and active in their lives. They found a home, a place prepared for them, a welcome."
One of the biggest questions for the Church is to ask whether Jesus Christ truly makes a difference to how we act. "Pope Francis spoke last autumn about too many churches being made up of practical atheists. We name the name of Christ but we don't let him change our actions."
Sin leads to great suffering, he added, citing the "lust for power" in the Middle East, leading to the hordes of fear driven-refugees.
"Our own personal struggles and suffering come back to a humanity that has cut itself off from God by pursuing autonomy," he said.
Archbishop Welby said that when he was at university, the attitude was that Christianity "was fine as long as it was not talked about, knew its place and did not interfere with one's life, and did not make unreasonable truth claims that might seem to matter."
He added: "It could be true, but it should not be so bad mannered as to say so."
Jesus is, however, still relevant today, although he does not offer the 21st century an apologetic on suffering. "What he does is come into this world and make our cries of being abandoned in pain and suffering his own cries."
People had become isolated from each other and from God.
"The call of Jesus to every human being is for purpose, not just drifting, to be a revolutionary without weapons, to be those who face the worst of suffering and known individually by God change the world in which we live. What an incredible purpose it is to which we are called to be a revolution without weapons. To change this bitter, dark world; that is the call of Christ to everyone here."
Archbishop Welby was met with an enthusiastic response.
Naomi Rose Steinberg tweeted:
Katie Graham tweeted: