The Christians of Extinction Rebellion, known as Christian Climate Action, will use Lent to raise more awareness about the climate crisis.
At vigils outside Westminster Cathedral and Westminster Abbey on Ash Wednesday, instead of making the sign of the cross with ash, priests will mark a cross onto the foreheads of worshipers using fake crude oil.
The group said the oil will be used as a symbol of "human mortality, as real oil is made up of dead matter, but also of human frailty as we are currently losing the fight against the over consumption of fossil fuels".
The initiative called '40 Days of Action' will encourage the Catholic Church to follow in the footsteps of the Church of England in regards to setting a net zero emissions target by 2030.
Throughout the '40 days of Action', members of Christian Climate Action will be holding a meditation vigil outside the Houses of Parliament. The vigil "will be focusing on lament for the climate and ecological crisis, and praying for leaders and representatives to find in themselves the courage to take urgent action".
The group has invited Christians to have their own climate-themed Lent. Christian Climate Action suggested taking steps to reduce their carbon footprint or that of their local church and taking part in civil disobedience to pressure governments to go net zero by 2025.
Nick Cooper, Christian Climate Action member said: "This is about system change triggered by personal growth. We invite everyone to journey with us into the wilderness of Lent and encounter the 'quiet voice' so often hidden from us in daily life.
"We need desperately to hear that sacred voice calling us together as a global community, to share what we have left, learning to live simpler more connected lives, and find the courage to take up civil disobedience in the face of an ever more desperate climate and ecological crisis. We need to take courage and stop denying the power that we hold as one sacred and interconnected body."
Dr Ruth Valerio, global advocacy and influencing director at Tearfund said Christians should use their prayer time during Lent to pray that politicians will take climate change seriously.
"The window to address climate breakdown is closing rapidly and the UK government needs to act by getting our finances out of fossil fuels overseas, increasing investment in renewable energy and getting on track to achieve our own net zero commitment.
"Lent, which is a time of reflection and commitment, is an important time to pray for our politicians to have the courage to take action. The physical presence of this vigil is a reminder of this."