Western Europe, and a part where the Catholic Church would be the only church
Christianity truly dominated the lives and culture of the people of Western Europe in this period. Something we can be sure of is that you would know the stories of the bible - they would be illustrated all over your parish church which would be the central hub of your community. The medieval world was a very visual one, and Christian imagery could be found throughout a town.
But how much doctrine and dogma would be known to you? After all, mass is given in Latin a language inaccessible to the average person at this time.
The eleventh and twelfth centuries had been spent reforming the Church at an administrative and theological level,* but the thirteenth century was the period when these changes were truly put into practice and the Church became the centralised power that we think of it as in the later Middle Ages.
Some examples of this:
Following the fourth Lateran council of 1215 all men and women were obliged to attend confession with their parish at least once a year.
The friars arrived in the early thirteenth century, they preached in the vernacular in towns and became very popular, ultimately disseminating christian thought to the masses.
It was also a period where the line between heterodoxy and orthodoxy were becoming more clearly defined. For example, if you lived in southern France there is a fair possibility you would have been asked questions regarding your faith by an inquisitor. In order to be orthodox you would need to know about the trinity, the sacraments and other areas of Church thinking.
Overall, while many aspects of Christian theology being taught in universities, such as Paris, would remain a mystery to you, you would still have a broad understanding of the central tenets. Christianity was central to your existence, and the existence of everybody around you. The documents we have often suggest an interested laity who were becoming increasingly involved in Church ideas in this period, particularly if we consider the growth of vernacular translations of scripture in this period.
*If you want to know more about these changes it’s worth researching the Gregorian reform and the twelfth century renaissance.
Sources:
R. W. Southern, Western Society and the Church in the Middle Ages
R. B. Brooke, The Coming of the Friars
R. I. Moore, The Birth of Popular Heresy