Answer :

it started to prove through different discoveries that many of the powers in our universe are not "God" and they have perfectly logical explanations, which threated the authority of the church as an absolute power

At that time, most people in society believe that religious authorities are crucial for the wellness of their society since they are 'close to God'. Because of this, a lot of religious authorities were given a high ranking position in the government.

Scientific revolution provide many advancement in technology and medical field that almost render the religions in western nations obsolete. Because of this, people start to turn their back on religious officials and they start losing their power in the government.