Is all sin created equal? Yes and no. You may have heard at one point or another in your life that all sin is equally grave; meaning, it all bears the same weight with regard to your salvation. While sin, in every case, opposes God, much of its effect on whether or not you’re eternally damned depends on well… you.
If I were to tell a lie, instantaneously, in order to avoid someone’s anger in a passing situation you would likely struggle to equate a ‘reactionary sin’ such as what I’ve mentioned with a premeditated murder. There are many in the fundamentalist school of thought who would assert that ‘sin is sin’ and that ‘all sin is the same in God’s eyes’. On the contrary, Sacred Scripture supports the idea that not all sin is of grave concern or ‘deadly.’ (cf. 1 John 5:16-17) The underlying truth we come to realize is that all sin points to a flaw within ourselves. We are all created in the image and likeness of God, but due to the fall we have an innate tendency towards what is pleasurable or sinful; this is called concupiscence.
The effects of our sinfulness are not altogether autonomous, because even though the nature of our sins can be radically different, their differing effects are all commonly involved. Sin is, essentially, an effort on our part that is in opposition to God, albeit direct or indirect. God is the only ‘true good’ that man can come to know and sin looks upon this ‘true good’ and chooses otherwise. Not only that, our sins are in opposition to our own human nature according to our nature’s ordering in the image of God’s divine nature. Just as Adam and eve were robbed of their paradise, so too are we robbed of perfect freedom when we sin. God created us to be free and to discover this true freedom that orients itself towards the good.
Sins can be distinguished according to their objects, as can every human act; or according to the virtues they oppose, by excess or defect; or according to the commandments they violate. They can also be classed according to whether they concern God, neighbor, or oneself; they can be divided into spiritual and carnal sins, or again as sins in thought, word, deed, or omission. The root of sin is in the heart of man, in his free will, according to the teaching of the Lord: “For out of the heart come evil thoughts, murder, adultery, fornication, theft, false witness, slander. These are what defile a man.” But in the heart also resides charity, the source of the good and pure works, which sin wounds. – CCC 1853
As we have already established, our sin can either be a direct or indirect effort. To further clarify, an indirect effort would be an instantaneous or reactionary sin that we failed to give full consent to, but committed it anyways. The Church recognizes these minor offenses as being venial. Venial sins wound the virtue of charity in our lives; however, they are not intentional, malicious acts towards God, who is the ‘true good.’ These types of sins point out a flaw or shortcoming in our spiritual life that must be attended to before it gets out of hand. Venial sins, as they relate to our communion with the Body of Christ are not acts that sever this relationship. We would do well to confess such venial sins, although not required, so that we might receive just penance as a preventative measure for future occasions of sin.
Beyond that, sin, as it relates to the disposition of man, can also be categorized as mortal or what the Scriptures call ‘deadly.’ Whether a sin is mortal or venial determines the vitality of man’s relationship with God. Mortal sin severs the bond between man and the larger body of Christ and, effectively, the bond between man and God. Mortal sin is to be viewed as a literal rejection or ‘turning away’ from God that results from the grave error of our choices. A murder that has been premeditated or, perhaps, the willingness to be unfaithful to one’s spouse are two examples of mortal sin. Sins that have been adequately considered and carried out regardless of the harm that may result are considered to be mortal. When man chooses such selfish behavior, he acts in complete opposition to God and his actions demonstrate a forsaking of his union with the true good.
“Therefore I tell you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven.” There are no limits to the mercy of God, but anyone who deliberately refuses to accept his mercy by repenting, rejects the forgiveness of his sins and the salvation offered by the Holy Spirit. Such hardness of heart can lead to final impenitence and eternal loss. – CCC 1864