Ever since I've returned to the Catholic church three months ago, I've been thinking more about sin. It's not as though I didn't hear pastors preach against sin before, just that I realized Catholics look at it differently - and, they look at it more often.
From the online site, New Advent:
The division of sin into original and actual, mortal and venial, is not a division of genus into species because sin has not the same signification when applied to original and personal sin, mortal and venial. Mortal sin cuts us off entirely from our true last end; venial sin only impedes us in its attainment. Actual personal sin is voluntary by a proper act of the will. Original sin is voluntary not by a personal voluntary act of ours, but by an act of the will of Adam. Original and actual sin are distinguished by the manner in which they are voluntary (ex parte actus); mortal and venial sin by the way in which they affect our relation to God (ex parte deordinationis). Since a voluntary act and its disorder are of the essence of sin, it is impossible that sin should be a generic term in respect to original and actual, mortal and venial sin. The true nature of sin is found perfectly only in a personal mortal sin, in other sins imperfectly, so that sin is predicated primarily of actual sin, only secondarily of the others. Therefore we shall consider: first, personal mortal sin; second, venial sin.
Protestants may accuse Catholics of separating sin into two categories but if I were the Protestants, I wouldn't exactly consider that a problem. Catholics may be accused of thinking too much of sin but Protestants, in my opinion, don't think of it enough. And this isn't even considering the non-denoms. From all my years involved with them; I can count on one hand the times I heard sermons that dealt head-on with sin. Again, this was my experience. Others may have had exactly the opposite happen.
I am glad to hear talk about "mortal" and "venial", sins of "commission" or "omission" because I so need to hear it. I have been forgiven through Jesus Christ, but it doesn't automatically mean my flesh has been subdued. Each and every day, I am presented with a choice. To sin or not to sin. As I recognize my adoption into Christ and ask for the grace of God through the power of the Holy Spirit to enable me to live a life pleasing to Him; God answers. But I am made aware that I need God more than ever. Being baptized into Christ isn't a one-time deal, making the believer saved and sanctified in one fell swoop.
In fact, I liken it a bit to buying a car. Imagine you bought a beautiful, shiny new car. It sits gleaming in your driveway and fills you with pride. But every now and then, you need to drive it. As you tool around the busy-crazy world, your precious car gets a little dirty, a little roughed-up. If you allowed this to happen for years without ever trying to clean it or properly maintain it with oil changes and the like - how would that car run after five years? Probably not as well.
The recognition of sin makes me realize how much I need the grace of God. Many talks from priests made me realize how sin displeases God. It separates me from Him until I realize that I have done wrong and must repent.
The Israelites were given the Promised Land, but yet they had to fight to acquire it. They weren't able to just waltz in there and say, "Well, you pagans...guess what? God gave us this land so if you would all quietly pack up and go, that would be just swell. I hear there's some employment opportunities in Egypt..."
No. The Israelites had to clean house in order to occupy the land. I think of my body that way. The Holy Spirit has to "clean my house" in order to occupy it. How would this happen without my cooperation, without my consent, without my repentance?
Catholicism keeps me on the straight and narrow as I realize my sin is obstructing my progress toward becoming a saint. It is a path for all of us and as far as I can tell, only the universal Roman Catholic church reminds us of this on a consistent basis.