Snake in paradise heart.

Where does sin come from? How to interpret the biblical narrative
of the serpent in paradise?
The third chapter of the Book of Genesis tells the history of the first sin – the temptation to eat the forbidden fruit, Eve’s conversation with the serpent-dragon, Adam’s consent, the expulsion from Eden. The Fathers hold that everyone’s experience confirms and prolongs in history what Genesis tells in the early chapters. Each of us owns paradise, a heart created by God in a peaceful state. And every one of us experiences the serpent that penetrates the heart to make us
seduce us. The snake takes the form of wrong thoughts. Origen writes
Many other Fathers agree with him that “the source and beginning of every sin are thought” (Greek logos).
And how can a simple thought be the cause of evil? It is not a simple thought but an impure, evil thought. In truth, what we call temptations are not even true thoughts, but rather images or fantasies that are accompanied by the temptation to do something wrong. St. Maxim the Confessor explains this situation with examples taken from everyday life, saying, for instance, that neither the ability to think nor thinking is evil. It is not hostile to be a woman. Nor is it cruel to think of a woman.
And yet, in the mind of a man inclined to sensuality. The image of a woman does not always remain pure but mixes with a carnal instinct that tempts one to act against the law of God. In the same way, money is not, and wine is not evil, yet they can become a stone on which a man stumbles because of the impure motives attached to them. So we say “pure.” Nothing else is added as we speak. For example, pure gold, pure water, etc. So are even thoughts pure until some motive is said to them that induces one to do evil?

Whence comes such impulses to do evil?
The Fathers liken the human heart to the “promised land” in which the Philistines, Babylonians, and other peoples cast spears and arrows, namely, evil temptations. These “evil,” “carnal,” “impure” thoughts cannot come from our heart, for God created it. They come, therefore, from “without.” They do not belong to our natural way of thinking. And as long as they remain “outside.” of us, they are not sinning. They become evil only at the moment when we consciously and willingly accept them when we identify with them. But the gospel says that evil comes from the heart and not from things (Matthew 15:19)
Certainly, but we must be careful how we interpret this text. Sin comes from a man’s heart because the consent to evil is given in the heart of man, his free will. Evil thoughts and passionate desires are almost always circling us. They often fill our imagination and our minds. They form man’s weakness for sin, of our ancestors. But they are not in themselves genuinely evil. The Church claims that lust comes from sin and tempts us to sin, but it is not a sin. And so we live in a dangerous state, constantly exposed to temptations. ..

How do we cleanse our hearts?
Man’s life on earth is a struggle, says Job (7:1). And one proverb adds: He who does not want to fight should not …nor live. But we must not exaggerate the difficulty of this struggle. The ancient mystical author, Pseudo-Macarius, compares our soul to a great city. In the middle is a beautiful castle, next to it in the marketplace, and then the periphery.
The enemy, namely original sin, has occupied the periphery, namely
our senses. And that is why we are often troubled there. But these disturbances typically penetrate the marketplace as well, …where we begin to debate whether we should accept an idea as our own or instead reject it. But into the castle of the heart, where our freedom is master, sin cannot penetrate unless we open the gates by our free consent. Even St. Teresa of Ávila speaks of the “castle of the interior” of our soul, where we can talk about our Lord, the divine Guest, without being hindered by outside interference. Despite this, we are inwardly divided. This is not pleasant.