The people on the right side did not support the ancient regime, they wanted a constitutional republic with a monarch. The people sitting on the left wanted to kill all aristocrats.
In the case of the french revolution the "left" would be the "intellectuals". (The buggers view is still alive and well in france.) The french believe that to be a Christian is equivalent to being totalitarian and despot (the poor folks don't know any better because they ran their Protestants off..tee hee). Hence Christianity (in all forms) is almost dead there.