1. over time the economy of europe changed from one based solely on agriculture to one focused more on trading and the merchant class, why did this transition take place?
2. how did europe transition from a system of feudalism to one organized into nation-states?
3. how did the catholic church react to those who disagreed to their teaching and practices during the middle ages?

1.    Over time the economy of Europe changed from one based solely on agriculture to one focused more on trading and the merchant class, why did this transition take place?

Around 3000 BC, influenced by the culture of the Middle East, emerged the first European culture, the Greeks, who structured around the so-called polis (autonomous communities) before this, predominated nomadic tribes, who based their survival in hunting and gathering. The foundation of the first cities (human conglomerates, where mutually it was contributed for social welfare). During this time, Europe was immersed in multiple wars, territorial issues until Alexander the Great undertook the conquest of the eastern world and this model prevailed after his death (323 a.C.)  

The Eastern powers returned to be independent, Macedonia remained like the high power, and therefore it became the great merchant, which transformed notably the interchange of goods and riches, in all the continent and its relation with North Africa and Asia.

2. How did Europe transition from a system of feudalism to one organized into nation-states?

From at least 250 a.C. and until 235, the Roman Empire prevailed, colonizing a large part of Europe, imposing its model of government and economy. In 313, Constantine decreed religious tolerance towards Christians in the so-called "Edict of Milan," while in 395, Theodosius the Great proclaimed Christianity as the official religion of the Empire. In this period, and particularly since the Council of Nicea onwards, Christianity developed strong hierarchical structures, in addition to actively developing doctrine and dogmas of faith. In that sense, Christianity began to create the appearance that the Catholic Church would present during the Middle Ages, and with the beginning of the Middle Ages, the fiefs created over the Roman colonies, took place as the city model, where the command of the feudal lord, the peasants and merchants received protection behind the walls of the cities, in exchange for security and payment of taxes. This model prevailed for centuries throughout Europe. It is generally considered that the empire ended after the fall of Constantinople under the Ottoman Turks in 1453.

The first signs of the renaissance of civilization in Western Europe began to appear in the 11th century, when trade began again in Italy, giving rise to the economic situation and cultural growth of independent city-states, such as Venice and Florence. At the same time, the nation-states began to take shape in places like France, England, Spain, and Portugal, although the process of their formation (usually marked by the rivalry between the monarchy, the aristocracy feudal lords and the church) it lasted several centuries. These new nation-states began to write in their languages instead of traditional Latin. On the other hand, the Holy Roman Empire, based essentially on Germany and Italy, was fragmented into countless feudal principalities or small city-states, whose subordination to the emperor was only formal.

3.    How did the Catholic Church react to those who disagreed to their teaching and practices during the middle ages?

After the Great Schism of East and West, western Christianity approved by the newly created kingdoms of Central Europe: Poland, Hungary, and Bohemia. The Catholic Church developed as a great power, giving rise to conflicts between the pope and the Emperor. In 1129 the Catholic Church established the Inquisition to make Western Europeans its members by force. The Inquisition punished those who practice heresy to repent. If they did not, they suffered the death penalty. During this time many nobles ruled the church. The monks of Cluny managed to establish a church where the nobles did not exist. Pope Gregory VII, continued the work of the monks with two main objectives: rid the church of the control of the kings and nobles and increase the power of the pope. The influence of the Catholic Church had grown enormously due to the conversions of pagan kings (Scandinavia, Poland, Hungary, Lithuania), Christian Reconquest of Al-Andalus, and the Crusades. As a result, most of Europe was Catholic in the fifteenth century.