
Christianity is a global religion centered on the life and teachings of Jesus Christ, who followers believe is the Son of God. It's a monotheistic faith, meaning Christians believe in one God who exists in three co-equal persons: God the Father, God the Son (Jesus Christ), and the Holy Spirit. Christianity is based on the Bible, with the Old Testament and New Testament serving as sacred texts.

The Crusades were a series of religious wars sanctioned by the Latin Church in the medieval period. The wars were largely in response to 400 years of Muslim wars of conquest in Christian lands. The most commonly known Crusades were the campaigns in the Eastern Mediterranean aimed at recovering the Holy Land from Muslim rule. Crusades were fought for a variety of reasons including the suppression of paganism and heresy, the resolution of conflict among rival Roman Catholic groups, or for political and territorial advantage.