The concept that all sins are equal is a common misconception in the Church. All sins are not equal. The remedy for all sins is equal. And, our acceptance of that remedy is always equal. There is no prescribed ‘penance’, so to speak. But sins themselves are not equal.
This is easily evidenced by the Old Testament. There are plenty of sins in the Old Testament which demanded physical death. And many which did not. Why would this be so unless some sins were weightier, in a sense, than others? Or, moreover, if all sins were equal, then what could be said about the ultimate sin of unbelief? There must be a sense in which some sins are greater than others.
In Mark, Jesus tells a scribe of the greatest commandment. Mark 12:29-30:
Jesus answered, "The most important is, ‘Hear, O Israel: The Lord our God, the Lord is one. And you shall love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’
If there is such a thing as the greatest commandment, then in would follow that the greatest sin would be to violate that commandment. And Jesus indirectly explains what that is.
Idolatry!
“The Lord is one”. In other words, there is one God. And we must love him with “all our heart and with all our soul and with all our mind and with all our strength”. But the funny thing is, virtually all sins are a violation of this commandment.
I believe that if we strip away the outer layers of virtually any sin, we discover idolatry under almost all of them. We lie because our success or esteem is valued more highly than God. We steal because we value that thing more than God. See the trend?
While most people don’t take seriously the sin of idolatry—or just consider it strictly in the literal sense—I think we should recognize that any time we find greater value in something other than God, we violate God’s highest law. When we realize this, it should become a source to praise God even louder for his grace and patience with us. And, become a motivator to look for and embrace the sanctification God is working in each of his children.


