Though this will be a short section it is important to include. The Catholic Church would claim that the categories of mortal and venial sin are established in Scripture (1 John 5:16-17). The church has taught that this simply means some sins, by their very nature, separate us from God eternally whereas ‘lesser’ sins like sins of omission or sins against charity, do not necessarily separate us from God. This is a debate I’ve had with my Mother before. If some sins, in their ugliest form, like child rape, murder, cannibalism, satanism, etc., can lead one to have no chance of repentance, then we might as well count out the apostle Paul, who wrote a good half of the New Testament and was a murderer of followers of Jesus before he met Him on the Damascus road in a blazing fire of blinding light. Yet it can be said that within Roman Catholic moral theology sins that are counted to be mortal have to be committed apart from ignorance, or in other words with full awareness of the evil involved. The gospel in scripture seems to say that no one is counted out of redemption when it comes to Christ. I don’t think one can just live however they please and then repent at the last minute. But I do think that some deliberate and grievous sins can be forgiven, and that person that enjoy the rest of a lifetime living purely for Christ while experiencing the consequences of their sin temporally, not eternally.
And my friend Anthony Simone, who is currently a seminarian, mentioned that according to the Catechism, a sin is only unforgiveable if the person refuses to accept forgiveness, called “blasphemy against the holy spirit”. Mortal sins in full awareness might be harder to reconcile, but can always be forgiven if asked and accepted. This is truly a biblical view.
So I’ve been led to understand that probably most people misunderstand the doctrine of mortal and venial sin, and potentially use it to justify certain sins they dislike more than others, and say that these certain “sinners” are counted out of a chance at salvation. I suppose many people do this- I’ve certainly seen it with evangelicals! I don’t even know where to begin with that! Haha. I’ve often seen many evangelicals treat people in the gay community as if there’s no chance they will ever follow Christ into a celibate lifestyle. I suppose when it comes down to it we just don’t have the perfect view that God has.
 Ibid., 121-122