"Depart from evil, and do good; seek peace, and pursue it." Psalm 34:14
We are commanded to "depart from evil". So what is "evil", what does it mean? We are also commanded to "do good". So what is "good", what does it mean? When we think about good and evil, we often define them as it relates to conduct- the way someone acts, what is produced. But they are more correctly defined as nature- the nature of something. Conduct is the behavior that is produced as a result of that nature.
For example, Jesus said that a good tree cannot produce evil fruit, and vice versa. Why is that? Because of the nature of the tree. It produces after it's nature. Apple trees produce apples, orange trees produce oranges, poison ivy produces toxic oils.
Before Christ became our Savior and Lord we were an "evil" tree. We produced evil fruit. Why? Because of our sinful nature. We had the same nature of our father the devil- even his name defines his nature: d-evil. (John 8:44) We had an evil nature and behaved in a wicked manner producing evil deeds.
Once we come to Christ we should then begin to produce good fruit because we have become a good tree. When we are born again, our nature changes, we get a new nature-- it's the nature of our Heavenly Father who is all good and all righteous. (John 3:7; 2 Cor. 5:17)
A tree is known by the fruit it produces. Likewise we are known by what we produce. Our conduct is the fruit that reveals what type of tree we are. If you have the nature of Christ in you you should do good because He is good. If you have the nature of the devil/sin in you you will do evil because he is evil. What you do, reveals which you are: a good tree or an evil tree. If you have the nature of Christ, then you should "depart from evil and do good".
Have a great day. If the nature of a person is evil, that person will conduct themselves in an evil manner. If the nature of a person is good because they have Christ's nature in them, that person will conduct themselves in a manner that is good.