I'll leave the question of whether you believe you are going to heaven or going to hell between you, God, and whether you're willing to ask forgiveness for that time you had sex in the church.
But as to whether the average (Christian) peasant in 13th century France knew enough about Christian dogma to believe in the Christian afterlife geography? Yes, absolutely.
I've talked many times before on AH about the Fourth Lateran Council in 1215 being a Big Deal for the Church, in terms of getting officially serious about reaching the laity--mostly with annual requirements of confession and the Eucharist. Of course, this took a pretty long time to spread comprehensively across western Europe.
To that end, I've also mentioned how in 1401, the villagers of Kraftshof wanted a parish priest in the first place, and in 1431, they asked for a priest who could actually preach. However, Lateran IV to the Kraftshöfers aren't really relevant here, and not just because Kraftshof is in the Holy Roman Empire.
Not hearing weekly sermons doesn't mean that a medieval Christian didn't understand basic tenants of Christianity, or thought Christianity was just the engine to make charms against sickness operate. Beliefs about the afterlife are one of the broadest and most clearly documented strands of religious knowledge and practice in medieval Christianity.
The most basic, but problematic, point is baptism. No, obviously the baby doesn't have a clue. However, the godparents of the baby must make the profession of belief on its behalf. By the thirteenth century, that meant reciting the Our Father and the Creed at the very least; probably also the Ten Commandments and increasingly the Hail Mary. The Creed contains several pesky little bits about heaven, judgment, and life after death.
But we're all familiar with the ability to recite things without processing or even understanding the words. (There are...several...real Latin words in this song, and they bear no grammatical relationship with each other, but I can sing the whole thing from memory anyway).
So let's look at practice. And there, we find that pre-death and funeral rituals are ubiquitous and very powerful. First, cases of suicide. Since suicide was considered a person's last act (please don't pedant about particular methods here), it was the ultimate unforgiveable, mortal sin--mandating hell. Under civil law, suicide meant a person's goods were automatically forfeit to whatever existed of local secular government. Under Church law, suicide meant you died outside the Church, away from God, destined for hell--and thus could not be buried in consecrated ground/a cemetery.
Looking at cases of people who committed suicide and were legally identified as such, or cases where people's family members fairly clearly covered something up, records always stress the important of the deceased person being buried in a cemetery. There's of course the practical motive here--I guess you might compare it to life insurance policies today that don't pay out if a person kills themselves.
However, while some peasants were quite well off--Joan of Arc's family is an A+ example--many of the suicide-related cases visible in records indicate very much the opposite. It seems that family members' or friends' priority was to make sure the dead person was able to be buried in consecrated ground, protecting their soul in the under/over/on-top-ofworld.
But we should also look at the case of still-living individuals and last rites. And this is where things get fun.
The Church hierarchy gets serious about the laity in 1215 because a lot of lay people have spent the previous century getting more serious about religion. This is not necessarily the same thing as getting serious about the Church hierarchy. That's true whether you're the Holy Roman Emperor appointing your own pope...or a shepherd in the Languedoc (southern France) deciding you don't particularly appreciate your parish priest shacking up with a "housekeeper."
(I promise the following is relevant.)
In the later 12th century, the Church decides there is a massive heretical movement sweeping across southern France, and launches a big theological and military crusade against it. Whether people's beliefs are heretical, orthodox, or "heterodox" in the sense that more or less everyone's beliefs are in the Middle Ages...this is a rather sprawling debate among historians. Basically everyone today will tell you that the idea of formal "Cathar" doctrine is kind of a retroprojection.
But there were definitely lay people who, when questioned, have some things to say that don't sound very enthusiastic about the Church hierarchy. Namely, sometimes they reject the services of the local priest in favor of a religious leader they call...wait for it...a "good man." Thinking face.
A lot of the testimony here, in fact, concerns last rites. Do people ask for the actual priest, or a visiting friar (Franciscan/Dominican)...or do they want a good man? Regardless, though, they're still wanting consecration, forgiveness, declaration of holiness, what have you, to prepare them for death--and life after death.
So sure--maybe a spinner living in Lyon lit candles in a circle around herself while praying to Mary Magdalene for help with her safe childbirth. Maybe a farmer living outside Paris never saw a single Eucharist host until his dying daughter received last rites. Even in a world where Christianity might to us seem more magic than knowledge, people knew they were headed somewhere after death--and evidently had a pretty strong preference about which "somewhere" it should be.