Christians are supposed to practice virtue and avoid sin. But what is virtue and what is sin. Someone might say that virute is doing that which is good and sin is doing that which is bad. True, but what makes one thing good and another thing bad. I think this is one of the major problems with modern society – due to our secular mindset we have no common ground on which to determine whether something is good or bad.
There must be an objective standard by which we can determine if something is good or bad. So what are we to do? We cannot rely on governments for that objective standard. Look at what has happened in America because the government has tried to determine good and bad: legal killing of the unborn, promotion of homosexuality, banning of prayer in public places, forcing employers to provide insurance that goes against their consciences (HHS Mandate), etc. No, the government is not good at determining right and wrong. Of course, that was never supposed to be the purview of government. Government is only meant to support that which is objectively good and enforce laws against that which is objectively bad.
There is only one Person who can give us the objective standard which we need to truly know that which is good and that which is bad: God. Yes, but which one, someone might say. The only One that exists, of course: the God of Abraham, Isaac and Jacob, the God who sent His Son Jesus Christ to die for the sins of the world. (Many might want to complain, “What about all the other religions?” If we have the right conception of God then we must admit there can only be One. And with one God there can be only one Truth. And with one Truth there can be only one Faith and religion by which to practice that Faith. Besides all that the question of which God or religion is the right one is outside the purpose of this post. And in addition to that I am a Catholic priest – would you expect me to say anything else?)
Therefore, taking into consideration that the God of the Christian faith is our objective standard for that which is good – because He is all Good – what is virtuous and what is sinful? Below is a quote from St. Basil the Great that can help us to understand.
This is the definition of sin: the misuse of powers given us by God for doing good, a use contrary to God’s commands. On the other hand, the virtue that God asks of us is the use of the same powers based on a good conscience in accordance with God’s command.
The key to understanding this has to do with God's command – or His will. What is it that God wills for us? Whatever He wills is necessarily that which is good and therefore virtuous. Whatever He does not will is therefore necessarily bad, sinful and should be avoided. Of course, the individual's conscience comes into play in the determination of what to do and what not to do. But all too often people will do something objectively sinful saying, “I didn't go against my conscience.” What such people do not understand is that each individual conscience must be formed by the objective standard of the Good set forth by God. And what is that? Jesus, who is God and therefore can be trusted, has revealed it to us. And the fullness of that revelation resides within the one Church that Jesus founded – the Catholic Church. So, if you want to know what virtue to practice and what sin to avoid then learn the teachings of the Catholic Church.