It would be great if people could trust themselves and their inner voice etc. But the problem with that is spirits can influence people easily and they don't even realize it.
If you can't trust yourself then how do you know someone else is NOT influenced by evil spirits. This is kind of the point of what I am saying. You know in your heart if you are about to do something someone else might consider to be evil. It is this voice which I would claim is the best authority for governing our actions. The problems with looking outside of ourselves is this will inevitable lead to mistakes or manipulation by others.
Absolute authority comes from within. Anyone who tells you differently is either trying to sell you something or enlist you as part of the power structure of their cult. This is what Satan does. Satan wants to be the only authority in charge. People who are not in line with Satan's ideology are sharing power and giving power to others as opposed to getting people to kneel to authority with blind obedience and loyalty.
Wisdom and understanding come from God. He is near us alright but we need the holy Spirit to really understand. You either are influenced by the Spirit of God or ... perhaps evil spirits.
I do not disagree with you our wisdom and understanding comes from God. But I disagree with you on your ideas of the source of evil. Evil does not come from outside of ourselves. The source of evil comes from our human imperfections. Our human imperfections cause us to have needs and desires. It is our needs and desires which are the source of all that is evil in the World. Therefore we, human beings, are the source of all that is evil in the World. Whereas God is perfect, whole, and complete. Since God is perfect, whole, and complete God has no needs or desires. Since God does not have any needs or desires God is absolute goodness in the highest possible degree.
If we aspire to be like God then we would try to live our lives with the least amount of needs and desires. Since our needs and desires are the source of all that is evil in the World. Or, if we cannot keep them to a minimum then we need to find a way to satisfy them in such a way that it does not create any evil. To deny or suppress our needs and desires only amplifies them making matters worse in the end.
Words and ideas only exist in our minds. They do not exist in reality. Where as acts of evil do exist and occur in reality. Evil spirits are not the source of evil in my opinion and way of thinking. The fundamental problem of evil is it is based on subjective opinion on what is to be consider evil or good. This is why I've come to the conclusion how we practice our religion or just saying magic words does not absolve us of our sins. The only way to attain absolution for our sins is by getting forgiveness from the people we have actually sinned against (or least in their minds based on their subjective judgments and opinions). My way of thinking about sin is much more anthropocentric and much more difficult to live a morally good life. You have to take very good care of your relationships with others in order to achieve salvation. When you create suffering in others you will inevitably live a life of suffering. Our brains have a nasty way of punishing our hubris with self-inflicting wounds.