How was Christianity spread during the Middle Ages?

During the Middle Ages, Christianity spread primarily through the efforts of missionaries, who traveled to convert various peoples, and through the establishment of monasteries that served as centers of learning and evangelization. Additionally, the endorsement of Christianity by political leaders, such as Charlemagne and other monarchs, facilitated its integration into the fabric of European society. The Crusades also played a role, as they not only aimed to reclaim the Holy Land but also brought Christianity into contact with different cultures. Furthermore, the Church established a network of institutions, including cathedrals and universities, which promoted religious education and reinforced Christian beliefs.