I disagree, mostly because the older we get, the more we get “in the head” and not “in the heart.” A first or second grader is still humble enough to take something to heart which they know by faith, but cannot understand intellectually. As we get older, we resist this more and more. Let’s face it: if our faith in the Eucharist and understanding of God’s mercy is all in the head, we are just sunk.
I think it is a good idea for confession and Holy Communion to start just at that time when we have both a more mature intellect and yet still have a naturally childlike heart. That is a good time to start the chosen habit of letting the mind be subordinate to the heart, to choose to retain that vital childlike attitude. It wouldn’t be good to try to forge that relationship when the head has been allowed to have the upper hand for several years.
It does take some great care to introduce the idea of mortal sin without making it into something that makes the children fearful of approaching God. I think the key is to stress over and over that it is the sin that we ought to run from, that the sin itself is its own punishment, that Hell isn’t something God does to us, but the ultimate in chosen slavery to sin, and so it is not God whom we should fear when we sin, but rather the sin itself, which is what harms us and condemns us. Sin teaches us to value something else over God’s love, and that’s what kills us, because God’s love is life itself.
First grade is not to soon to know that we and our choices matter, and matter a lot. As I tell my students, God loved us enough to give us real choices that have real consequences. We aren’t insignificant, we aren’t machines that have to react a certain way to some outside prompting. We have free will, and what we choose truly matters. That is the only way we can be given the gift of loving freely, is to have been given the real choice of refusing. That gift, the gift of loving by choice, is so beyond any other gift God could have possibly given us, because it is what it means to be in the image and likeness of God, that it merits the chance that we would refuse it.
As the Catechism 1422, speaking of eternal and temporal punishment, puts it:** “These two punishments must not be conceived of as a kind of vengeance inflicted by God from without, but as following from the very nature of sin. A conversion which proceeds from a fervent charity can attain the complete purification of the sinner in such a way that no punishment would remain”** So venial sin needs to be presented as something that does real damage, too. Like physical damage, even though there is a stark difference between dead and alive, there is a whole continuum from less harmful to deadly.