He did evil because he had not set his heart on seeking the Lord
He had not prepared his heart
He had not made his heart ready
He had not established his heart
He had not made his heart steadfast
He had not set his heart in the right place
...to seek the Lord
The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. Galatians 5:19,20
All of these (and other) sins are not in themselves the key issue, they point to a larger, more fundamental departure. Sins will never be overcome by trying hard not to do them, the heart needs a different attention, to be captivated by something or someone else
When Jesus was asked which is the greatest commandments, he answered to love God and to love your neighbour. He then went on to say, "All the Law and the Prophets hang on these two commandments.” Matthew
22:40. If we get these two commandments right then we will find ourselves fulfilling all of the rest of the law
Matthew
6:33 makes a similar point, "But seek first his kingdom and his righteousness, and all these things will be given to you as well." Fix your attention on the highest and greatest and you will find the rest of your needs being met
Seeking the Lord will have the same impact on sin, get our priority right in our pursuit of God and we will find a declining inclination to sin. Focus on not sinning and we will try to do it in our own strength and fail, focus on seeking God will result in us sinning less
Sexual immorality, impurity and debauchery have at their root cause a desire for pleasure that is not found in God. Idolatry and witchcraft are the rejection of the one true God for a god made in our own image. Discord and jealousy happen when we elevate ourselves in importance and lessen the importance of God.
Fits of rage are the outcome of a life whose heart has not been softened by living in proximity to the Prince of Peace. Selfish ambition results from a heart that has a wrong focus, a heart that is not pre-occupied with seeking the Lord. Dissensions, factions and envy overflow from lives that are not focused on Christ and his kingdom. Drunkenness, orgies and the like will always occur when people get bored with life rather than set God as their life's goal
Whatever the sin is that causes us to stumble we should realise that it is 'the other sin' that is the real issue