Father Martin Newell, 80-year-old Phil Kingston, 53-year-old Ruth Jarman, 39-year-old Westley Ingram and 32-year-old Helen Whitall whitewashed the walls of the Department for Energy and Climate Change (DECC), last November.
The incident coincided with the first day of the climate conference in Paris and also saw the five, who belong to Christian Climate Action, using black paint to rebrand the department the 'Department for Extreme Climate Change'.
The defendants, who represented themselves, did not dispute their presence at the scene or the actions attributed to them, but argued that they had a 'lawful excuse' under section 5 of the Criminal Damage Act.
Found guilty at Hammersmith Magistrates Court in west London yesterday - while their supporters prayed and held a vigil outside - they must each now pay £340 in fines.
Speaking after the verdict, Father Martin Newell commented: "Pope Francis has called on Christians to go further in opposing climate change and we have tried to answer that call in faithfulness to Jesus who was also tried and found guilty by a court."
Ruth Jarman from the group said: "We do not agree with today's judgement. The point of the law is to maintain justice, stability and order.
"Climate change threatens all these things so fundamentally that the law should be used to defend those who are trying to stop climate change, not those who are creating it.
"We think DECC should have been in the dock, not us. The department speaks fine words, but its actions scupper any possibility of sufficient global action on climate change.'
Helen Whitall added: "What we did was reasonable under the circumstance. As a Christian I feel that whilst it is essential to always act out of love for God and others, I have a responsibility to speak out against injustice to protect all that God loves, human and non-human, which may at times involve non-violent direct action in the tradition of Christ and the prophets where I feel justice and truth are being silenced."
The group has received support from a number of theologians.
Michael Northcott, Professor of Ethics at the University of Edinburgh, said: 'Without such acts in the history of the United Kingdom, the vote would not have been conferred on non-land owning citizens, nor on women, and we would not have ended slavery, or forced child labour in our factories.
"Civil disobedience is essential to democracy provided it harms no one. The actions of these protestors were a non-violent and peaceable way to expose the hypocrisy of current UK government energy policies.
The Department for Energy and Climate Change told Premier it would not be commenting on the outcome of the case.