Cardinal Vincent Nichols has been speaking as Colombia's President visits the UK in the first-ever state visit here.
Juan Manuel Santos de Calderon has been invited as an official guest of Her Majesty the Queen.
Cardinal Vincent Nichols, Archbishop of Westminster, said: "Throughout five decades of violence and bloodshed in Colombia, the Catholic Church has provided support and accompaniment to countless victims of conflict in their quest for justice, reparation and lasting peace.
"This peace process is now in a further, challenging phase.
"I welcome every effort by all involved to bring that lasting peace to Colombia and a better future for all its people."
Fighting between government forces and FARC gorilla soldiers have killed more than 250,000 people to date.
There are an estimated eight million victims and the country has the world's largest number of internally displaced people, 6.9 million.
Last month President Juan Manuel Santos won the Nobel Peace Prize for his efforts to bring an end to the bloodshed.
Other religious leaders, including Pope Francis have spoken hopefully about the country's move towards a new peace deal.
The proposal for lasting peace was narrowly defeated by referendum, peace has held since and negotiations are underway for a new agreement.