What were the causes of the Great Schism of 1054 CE?

The Great Schism is the divide between Christians in the East and West and split the Roman Empire in two. This divide was created due to differences in theology and beliefs on how the church should be run as well as political issues between the two factions.
Theological differences included disagreements over whether the Holy Spirit is derived from God the Father or from both God the Father and the Son of God, Jesus Christ. There was also much disagreement about the supremacy of the Pope. The western Christians believed that the Pope has supreme authority over the Church, as ordained by God. Other disagreements included whether bread used during communion should be leavened or unleavened.
Political issues were derived from the theological differences between the two orthodoxies and came to a head when the Greek/Byzantine churches in Italy were forced to either change their views or close their doors. In response, the Eastern Orthodox church gave the same ultimatum to the Roman Catholic churches, which led to the patriarch of each orthodoxy excommunicating the other.