Diminishing powers of the Roman Catholic church in international matters

Question

Before Enlightenment and Renaissance, Church or Pope had some powers which were almost same as what international organization may have.

for example:

After the fall of Constantinople in 1453, Europeans had to pay very heavy price to the intermediary Arab traders for importing goods from India.
It was in this background that the Pope, by an order called Papal Bull, authorized the two European States - Spain and Portugal - to explore all alternative water routes to India. After discoveries of new lands Pope draw a arbitrary line ,on map, from north to south, and authorized Portugal to establish her monopoly over the east and Spain over the west of this line.

So, during Enlightenment and Renaissance period which particular incidents or events were responsible for diminishing these powers from Church or Pope?

Answer 1

The incident you asked I suppose is the Westphalia treaty, or the Peace of Westphalia (1648).

In the field of international relations the treaty is widely acknowledged as a big turning point in European history, as it established each nation as a sovereign states which hold sovereignty under its own. It happened before the Enlightenment era and closely related with all the religious discontent that sparked Enlightenment.

Before Westphalia, politics and religion often intertwined. People follow state leaders in the same way they follow their priest. Secular conflicts is seldom far away from religious conflicts. As such, the Pope, as the holder of highest position in religious matter, often acted as the prime authority in dispute between states.

This changed with the rise of Protestanism, as @T.E.D. suggested. Pope no longer have the authority to settle dispute between states as there are several powers which did not recognize Pope's authority. Conflicts between states kept going on, until it became the war now known as The Thirty Years' War, the conflict between Catholic states vs Protestant states.

The Peace of Westphalia was born directly from the war. Europeans realize they need to maintain a stable international political system without direct involvement from religion. This is supported by the Enlightenment zeitgeist that religion should be less involved in politics. There they have thinkers such as Thomas Hobbes and Montesquiue, whose ideas later developed by Thomas Jefferson (of USA).

Answer 2

I believe in this matter, the Pope was acting much like we use the UN or international standards organizations like IETF or ISO today: as an independent international organization respected by all parties.

The main factor that diminished this authority was the rise of the protestant northern countries (England, Holland, and much of Germany). Protestant countries (by definition) didn't recognize the Pope's authorithy, and had no compunction about carrying out their own overseas explorations (or siezing those of the Iberian countries).