The Clergy

cartoon representation of the confiscation of church lands

The National Assembly resolved the immediate financial crisis by seizing church lands and in The Civil Constitution of the Clergy putting the church under the control of the State. Abbe Sieyes fiercely resisted the passage of this legislation and accused the other delegates of "bourgeois envy." But he was overruled. The measure was very controversial to a nation of Catholics and drew support away from the new government.
This legislation (and legislation imediately before and after it) significantly reduced the power of the Catholic Church. The Church had been the largest landowner in France. The state took over this fortune in property and issued a paper currency, assignats, backed by confiscated church property. Priests were now employed by the state. Clergymen were required to swear an oath to the new constitution. Many refused to swear the oath and were placed under arrest.

http://www.historywiz.com/civilconst-clergy.htm