People doing good for others are "lights of kindness" shining out in difficult times, the Archbishop of Westminster said in his homily at Midnight Mass.
Preaching at Westminster Cathedral, Cardinal Vincent Nichols spoke of finding God's mercy in "times of uncertainty and an absence of consensus".
He said: "God chooses to show the might of his love in a place of poverty and simplicity. God chooses to enter our world not in a palace or as an enforcer but by the route of human weakness and need.
"Here we see that God’s use of power is so different from the way in which we so often use the power we have. In entering our broken world God gives priority to places of despair and poverty. This is so radically important.
"Here we learn that this same priority is a pathway to the fulfilment and beatitude which is God’s intention for us. Only by having this same priority will the mighty of our world find the wisdom we truly need at this time. Only by taking this same perspective will the powerful come to see that their first and ultimate duty is service of the people in their genuine need. This, too, is at the heart of Christmas."
Speaking as he begins his fiftieth year as a priest, and after recovering from a brief illness last month, he continued: "I become more and more aware of how difficult it is to find the right word, or image, to help us appreciate this moment."
He described the cathedral off Victoria Street, decorated with thousands of lights.
"Christmas lights are everywhere. For me each light represents an act of kindness. In my eyes these countless lights come to represent the countless acts of kindness that so characterise our society.
"Yes, it is true, our society is full of generosity and compassion, although we do not shout about it. Constantly people respond to need, with quiet dedication and goodness. Yes, we are in difficult times, times of uncertainty and an absence of consensus. Yet these lights of kindness shine brightly in that surrounding darkness."
In Westminster diocese alone, there are more than 130 projects responding to food poverty and homelessness. Many schools provide breakfasts and vouchers.
In St Patrick's Cathedral in Armagh, Archbishop Eamon Martin, Archbishop of Armagh and Primate of All Ireland, said: "On this Christmas night, as we marvel at the wonder of the universe, let us pledge to care for Planet Earth, our common home, by being less wasteful, and more conscious of the damage that we can do to our environment by selfish living.
"As we reflect on the Christ’s birth in the poverty of the stable, may we always be thankful for the food we have to eat, for our health, and for the warmth and security of a home; may we be more conscious of those less fortunate – the poor and the hungry, the sick, the lonely.
"As we contemplate this Christmas the Holy Family of Jesus, Mary and Joseph, let us pray for our family members at home or away, and spare a thought for families who are wounded or separated by war and violence, distrust or relationship breakdown.
"And, as we gaze in wonder and awe at God’s presence in the newborn infant Jesus, let us bring to mind children who bring so much joy and happiness into our lives. We pray that all children – born and unborn – will be protected from violence, trafficking, abuse, abortion, neglect or exploitation."