Nicky Gumbel, vicar of HTB and pioneer of the Alpha course, has written a one-off column for the Express newspaper on what Jesus' birth means amid "post-truth" politics.
In the Sunday column he wrote that Jesus's gift of grace and truth at Christmas is necessary antidote to leaders "denying facts or say things that are distortions of the truth".
He wrote: "The world is missing the truth and grace".
He added: "Jesus came full of truth but he also came full of grace. Grace and truth go together. We need both."
Gumbel is the innovator behind the Alpha Course, an evangelical course that takes people through the basic beliefs of Christianity. More than 27 million have now taken the course across 169 countries in 112 languages.
Gumbel's evangelical article on Sunday explains the Christian theology of God's grace.
"Grace is undeserved love," he wrote. "Truth needs to be softened by love but love needs to be strengthened by truth."
He added: "If someone punches you in the face and you don't punch them back, that is mercy.
"If someone punches you in the face and you don't punch them back but instead say, 'That's OK, you are forgiven,' that is forgiveness.
"If someone punches you in the face and you don't punch them back but instead say, 'That's OK.'
"And then you buy them an ice cream. That is grace. This is God's love for us.
"He doesn't treat us as we deserve. He does not get his own back on us. He forgives us. He is the Saviour.
"If the greatest need for this world was for pleasure God would have sent us an entertainer.
"If it was for money he would have sent us an economist. But as our greatest need was forgiveness he sent us his son to die on the cross – a saviour."
