To us today it all seems very strange - even the language was different

The language of most of the people was Saxon English but the languauge of the church was Latin.The language of the court was Norman French. Very few people could read so how did the village priest teach his congregation? They were expected to know
The Creed
The Pater Nosta - The Our Father
The 10 Commandments and the 2 New Testament Commandments
The 6 Points of Faith
1. The seven deadly sins  pride, envy, wrath, lust, gluttony, sloth, avarice
2. The seven cardinal virtues humility, charity, meekness, chastity, moderation, zeal, generosity
3 The seven works of mercy: corporal
4 The seven works of mercy: spiritual ( the priest was expected to do this)
Feed the hungry To teach the ignorant
Give drink to the thirsty To counsel the doubtful
Welcome the stranger To chastise the sinful
Clothe the naked To comfort the sorrowful
Visit the sick To forgive enemies
Visit the prisoner To suffer tribulation
Bury the dead To pray for all fervently
5 The seven services of the Opus Dei Lauds, Prime, Terce, Sext, Mon, Vespers, Compline  Plus the Mass
6 The Seven Sacraments  - Baptism, Confirmation, Holy Eucharist, Holy Anointing, Holy Matrimony, Holy Orders, Penance

In a world where life was short and difficult, where folklore and superstition were still rife the church offered hope and a future beyond this life. Just because they could not read should not make us think that everyone was unintelligent.  Everybody went to church, regularly and often. Wall paintings, stained glass, carvings in wood and stone depicting Bible stories and the lives of the saints were all used to teach different aspects of the faith. The images with their symbolic language would have been very powerful for medieval people.

Reference The Seeing Stone Chapter 7 My Tail Bone - Arthur remembers the picture of Adam and Eve with the devil on his church wall.