You should read the book I recommended you yesterday, A christian view of men and things
It answers your question
It was the enlightenment philosopher Rousseau who wrote what is considered the "manifesto" for the french revolution. He began by asking the simple question "how is state coercion justified?" Given that we "ought" to obey the government something has to justify this. We ought not obey our neighbour in a similar way. It is this fact Rousseau sought to explain.
He rejects the notion that government is authorized by God and instead proposes that government is authorized by a social contract, ie. all members have once upon a time come together and given up their naturali rights in order to be ruled. They did so because the obstacles (for survival) were too great to overcome by the collective effort of the citizens and a greater power was needed. Moreover, all citizens have certain interests in common and government is thus authorized to promote the "common interest".
At this point we thus have two assumptions: what government does lies in your interest and the people by itself does not always seek what is best for them (othewise no contract would have been needed). Also, government is needed otherwise the species will perish. Government is also infallible since it always seeks the common interest. Government therefore provides you with morality and life, things you would not have had without it.
Now - government can be corrupted and not represent the common interest (which now has become God, and the politicians its high priests). Then it needs to be replaced (revolution)
After a revolution there is always a risk for another revolution (since someone else might have another opinion of what the common interest is). So dissenters have to be destroyed (since they threaten the well being of the whole state - what if their ideas spread?) so that order can be established.
Moreover the state has to bind the conscience of its subjects. Obey the government, the survival of the race depends on it.
Religion is dangerous, christianity especially since it directs the peoples conscience towards God and not the state. The secular state is jealous and will not tolerate another authority. It is not safe if people get exposed to ideas about God.
I cannot say that this is 100% how the French revolution happened, but at any rate it is the logic of enlightenment politics.