Many Catholics believe that most, if not all people, will go to Heaven.
One reason they give for this belief is the Church’s criteria for a mortal sin: They say you can’t commit a mortal sin unless you are fully aware that committing the act will cut you off from God’s grace and imperil your soul. No one would deliberately cut himself off from God’s grace and go to Hell if he were fully aware of the consequences of doing so — unless he were insane, in which case he can’t be held responsible for his decisions, and therefore can’t commit mortal sin.
By this criteria, they say, hardly anyone could ever actually commit a mortal sin, even when they fear they have done so. Therefore, Hell must be sparsely populated.
But are these really the criteria for a mortal sin?
The Catechism teaches the following: “For a sin to be mortal, three conditions must together be met: ‘Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent.'” CCC 1857. But this doesn’t say what “full knowledge” and “consent” consist of. Full knowledge of and consent to what?
A couple paragraphs down we find an elaboration: “Mortal sin … presupposes knowledge of the sinful character of the act, of its opposition to God’s law. It also implies a consent sufficiently deliberate to be a personal choice.” CCC 1859.
It doesn’t mention full knowledge of cutting yourself off from God’s grace and all that entails.
First, strictly speaking, no human being can have “full knowledge” of all that God’s grace entails. Being finite beings our knowledge is necessarily imperfect, especially where God is concerned. But aside from that, according to the Catechism the knowledge required for a sin to be mortal is not full knowledge of the consequences of the sin, but simply, knowledge that the act is a sinful act.
As to full consent, again this doesn’t mean full consent to being cut off from God’s grace and all that that entails, based on a full knowledge of those matters; but merely, “a consent sufficiently deliberate to be a personal choice”.
In other words, a mortal sin requires you make a personal choice to commit an act involving grave matter, which you’re fully aware is sinful. So if you know full well that adultery is sinful, and make a personal choice to commit adultery, you have committed a mortal sin.
Basically these people are saying that the gate is small and the way is narrow that leads to damnation, and there are few who enter through it. But this turns Jesus’ teaching on its head, since he says, “[T]he gate is wide and the way is broad that leads to *destruction*, and there are *many* who enter through it.” Mt. 7:13.
The narrow gate is the other one.