“Do not be adulterous after your eyes”- Hashem judges based on each person’s level:[1]
In the Parsha of Vayomer, the third Parsha of Shema, the verse states “Velo Sasuru Acharei Levavchem Veachareiy Eiyneichem Asher Atem Zonim Achareichem/Do not stray after you heart or eyes of which you perform acts of adultery.” The word Zonim literally comes from the word Zonah, which means a harlot, or one who performs adultery. The verse is teaching us that when one sins, he is considered similar to a married woman who has committed adultery. Just as a married woman is in a relationship with her husband, and breaks the trust and bond of that relationship through adultery, similarly a Jew is in a relationship with Hashem and when he sins he breaks the bond and trust that was shared with Him. A sin substitutes the love of Hashem for the love of the physical and corporeal world similar to a woman who has left her husband’s love and gone astray with the love of another man. Nonetheless, only a Jew that first attained a relationship with Hashem can be truly viewed as a Zonah and adulterer when he sins, as only in such a case is he truly substituting his current relationship with Hashem with that of another. However, one who has never merited seeing the light of G-d, and is not found in a relationship with Hashem, cannot be called a Zonah when he sins, as he has never seen the light, and hence substitutes darkness for light. It is therefore understood that the former type of sinner causes a lot more pain to Hashem than the latter, and he must do greater Teshuvah in order to be ready to be reaccepted by Hashem and receive from His Divine light. Now, although in truth every Jew is in a constant relationship with Hashem, even if he is unaware of it, nonetheless one can’t compare the quality of the relationship between one who knows of his relationship and one who does not. Thus, the more a Jew internalizes his relationship with Hashem the more he must distance himself from straying from Him in even subtle matters.
[1] Likkutei Torah Korach “Vayikach Korach” page 52b