There is no understanding those that do evil. They walk in the flesh, and there is no good in the flesh, because they are of the world.
You can’t expect good to come from those that are of the world. Therefore, what do you expect? And, what more is there to understand?
Those that follow after Jesus are not of this world, for they walk in the Spirit.
You will know whether someone is of the Spirit or of the flesh. Try them. Any person, in the flesh or the Spirit, is know by what they produce – by their fruit. Either good fruit, or evil fruit.
Ask yourself, what type of fruit are you producing?
Matthew 7:17-18 (KJV) – even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. A good tree cannot bring forth evil, neither can a corrupt tree bring forth good fruit.
John 17:16 (KJV) – they are not of the world,even as I am not of the world.
Galatians 5:16 (KJV) – this I say then, Walk in the Spirit, and ye shall not fulfill the lust of the flesh.
I John 4:1 (KJV) – beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.
Matthew 12:33 (KJV) – either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is know by his fruit.