Regarding the verse: "Every man when his wife goes astray,"1 which opens our Parashah with the laws corresponding to the woman who deviated from modest conduct ("sota"), our Sages2 comment: "A man does not transgress unless a foolish spirit has entered him." (The term the text uses to say "goes astray” is tiste, with the same letters as shtut, which implies foolishness, since the deviation from modesty, and infidelity, is closely related to foolishness and idiocy.
This saying of the Sages offers an explanation for a phenomenon that is astonishing at first glance: every Jew, whoever they may be, possesses deep within their soul an unwavering love for the Most High. They will choose, without hesitation, to give their life for the sake of sanctifying His Name and to avoid practicing idolatry. Given this, how is it possible for a Jew to transgress through sin, an act that separates and distances them from Hashem? How can one allow themselves to carry out an act that contradicts their faith and inner conviction?
AN ALIEN SPIRIT
The answer is that a foolish spirit entered him. He was dominated by an alien spirit, a spirit of foolishness, which obscured the faith in his heart. It is this spirit that caused his insensitivity to the gravity of his actions, which leads to his separation from God. If he had truly understood the meaning of sin and transgression, and the fact that they distance one from the source of holiness, he would not have sinned under any circumstances.
What is this foolish spirit?—material desire. Materialistic and carnal attraction causes man to lose spiritual sensitivity and the feeling of attachment to the Most High. He deceives himself, thinking that nothing happened and that despite the sin he remains faithful to Judaism and close to Hashem. The desire for pleasures obscures the truth: that every sin, even the slightest, damages the bond of union with God.
GOOD IN HIS INTIMATE SPIRIT
On the other hand, since the root cause of sin is that 'foolish spirit' that obscures the truth, it turns out that even when a person sins, it doesn't mean they are inherently evil. On the contrary, deep down they are good, devoted to God, and don't desire to sin; it's just that the spirit of foolishness took hold of them and caused them to transgress. Sin is something external and not part of the person.
We learn this way of viewing sin from the verse "when his wife goes astray." And this is not accidental. There is an essential relationship between the general concept of sin and the sin of the woman who deviated from proper conduct toward her husband.
THE JEWISH PEOPLE AS WOMAN
The bond between the Most High and the people of Israel is often compared to the relationship between husband and wife. Hashem is 'the man' and the Congregation of Israel 'the woman'. When a Jew sins against God, it is like a woman who turns her back on her husband, like that woman who strayed from modesty and fidelity. Therefore, it is specifically the case of the woman who strayed (the 'sotah') that the Torah chose as an example to teach us the nature of sin.
The analogy with the woman who 'went astray' ("sotah") also expresses a positive aspect. The "sotah" is not a woman who is certain to have sinned; she merely acted improperly, arousing suspicion. And the Torah assures us that if it ultimately turns out that she is pure and innocent, "she will be cleansed and conceive offspring."4 This is how it is with the Jew: despite having sinned, deep in his heart he remains united with Hashem, and therefore he will ultimately do Teshuvah and return to His path, since he will not be rejected by Him, not by anyone.5.
(Likutei Sichot Volume 2, Page 311)
NOTES: 1.Bamidbar 5:12 2.Sotah 3,a 3.See Sefer HaMaamarim 5710 Page 114 onwards 4.Bamidbar 5:28 5.Shmuel 2 14:12 (with some idiomatic variation)