So basically there were five causes:
1.Political problems After Louis XVI became king,under his poor rule,problems in France became even more serious.People were discontented.
2.Economic problems Court expenditure and foreign wars spend a lot of money,also tax officers were corrupt and reduced income of government.When France was hit by natural disaters,peasants had no income to pay for taxes.
3.Social problems France was divided into three estates,the first(clergy) and second(nobles) estates didn't need to pay taxes and enjoyed many privileges.
4.Influence of Englightenment thinkings there were many famous Englightenment thinkers in France such as Voltaire, Rosseau, Montesquieu,etc.They encourged equality in society and the right to rebel.
5.Impact of success of American revolution After the success of American revolution,Englightenment thinkings were more supportive by the people,the middle class were determined to fight against for equality and freedom.
Yeah because the French Revolution was such a great time with murder, beheadings and betrayals (and rank atheism) are you sure you want to tie your church to this?...