In 1215 which is the year the King John was forced to sign the Magna Carta, the Fourth Lateran Council was held. While the Magna Carta is considered to be a huge event today it did not affect the lives of the general population in Europe while the Fourth Lateran Council was a HUGE event during contemporary times. This was this council which vastly transformed the Catholic Church into the Church as it is today. Some of the decrees issued at the council were: Participation in mass on a regular basis was now a requirement. Taking communion and going to confession were required at least once a year. The doctrine of Transubstantiation which declares that the bread and wine of communion become the actual body and blood of Christ is declared. Marriage became a sacrament instead of just an economic arrangement. Priestly celibacy was deemed a good thing at the Second Lateran Council but now it became a requirement to enter the priesthood.

(The Great Courses – Turning Points in medieval History)