The spread of Christianity and the power of the Church in medieval Europe can be considered the most important factor in shaping medieval economic behavior. Fundamental Christian doctrines had a profound influence on medieval economies. Christianity was very cosmopolitan and sophisticated in spirit. It taught a theory of brotherhood that embraced all races and classes and was not limited to the local community. Medieval Christianity taught about the natural equality of man as opposed to older doctrines, which held that men are all different by nature.
The Church prohibited Christians from enslaving other Christians. Slaves who belonged to believing Christians were to be set free as soon as they converted to Christianity. Along with the doctrine of equal rights and brotherhood came the idea of the natural communality of property. This idea or doctrine declared that according to the laws of nature, men owned everything in common and as a community.
Another Christian doctrine concerned itself with the dignity of labor, which was in direct opposition to the ideas advocated by ancient civilizations. The doctrine called for the appropriate recognition of those who toiled and worked hard, i.e. those who ate the bread from the sweat of their brow. Christianity espoused good work ethics and praised those who worked hard. The Biblical aphorisms devoted to the advantages of diligence and determination in work were very important to medieval society.
Almsgiving and charity were basic and essential virtues that are not only mentioned in the Old Testament, but stressed in both spirit and word. In his writings to his son, St. Louis Marie De Montfort says, "Dear Son, have a tender and pitiful heart for the poor, and for all those whom you believe to be in misery of heart or body, and according to your ability, comfort and aid them with some alms." This quotation illustrates the two limitations that medieval churchmen placed upon the giving of charity.
These limitations stated that alms and charity were to be given only to those who were in genuine need, and that any charity must be given in proportion to the wealth of the giver. During medieval times, charity was a duty and incumbent upon everybody of means. It was also a way to recognize the obligations of the wealthy in rectifying social injustice. Christianity also preached the perpetuation of the family and family life.
Through these doctrines, Christianity introduced new elements that had been missing from the Roman form of government. The Church said that these principles laid the foundations of a viable economy. Together with an emphasis on the personality of man came an increased acceptance of man's worth and the introduction of humanitarian and moral ideas. These ideas placed restraints upon the individual while at the same time advancing his duties and rights.
It should be noted that the idea of charity was often considered a noble end rather than a means of helping the poor in particular, or society in general. The same was true of manual labor. Hard work and discipline were seen as ways of attaining salvation rather than a means of acquiring wealth. People did not take pride in their craft and there was no interest in the final outcome.
In medieval times, agriculture was seen a praiseworthy endeavor and manufacturing was not believed to be displeasing to God; trade for profit, however, was frowned upon. Material wealth was fatal to one's spiritual welfare, but was permissible if it was used to benefit one's fellow man. Christianity strictly forbade usury because the act of charging interest on a loan, thereby increasing the value of the original sum, would cause an injustice to the borrower.