Andy Lester from the charity A Rocha was speaking after world leaders struck the draft agreement after all-night talks at the end of a two-week conference.
It is hoped ministers from countries all over the world will officially settle on the legally binding deal by the end of Saturday, though there may be opposition from some nations.
The draft deal commits to ensuring global temperatures do not rise more than two degrees celsius above pre-industrial levels, and is aiming for them not to rise above 1.5 degrees celsius.
Major world nations will have to make very significant changes in order to meet the target.
Andy Lester told Premier if countries could meet the targets then very serious effects of climate change like sea levels overtaking land could be averted - effects which overwhelmingly affected poorer, developing nations the worst.
Because of this, he said: "We as a Christian community have got to put our government under pressure to change its policies, change the mindset and get them seriously active on climate change now, otherwise the whole proposal we've got in front of us will be meaningless.
"The government's undone a lot of green subsidies and tariffs... If countries like the UK are seriously going to meet that objective of under two degrees they've got to have incredibly ambitious plans on renewable energies.
"This is a good milestone but the really hard work starts now. This is the beginning, not the end of the process."
Listen to Premier's Aaron James speaking to Andy Lester here:
