Our Gemara on Amud Beis tells us that there is a distinction and potential stringency in regard to someone who employs a trick to cook from one day of Yom Tov to the other versus one who intentionally cooks. If one cooks a number of items on day one of Yom Tov rationalizing that it is all for day one, knowing full well that he really is cooking for day two, the food is forbidden. Yet, despite this, the Gemara considers that if one intentionally violated Yom Tov and cooked from one day to the next without any rationalization, the food might still be permitted? Why?
Rashi explains that a straightforward wicked person will not dilute others’ observance. They will not mistakenly learn from his actions as they can plainly see he is a scofflaw. However, a person who employs trickery and rationalizations comes off to himself and others as righteous, and this will mislead others.
Though Rashi’s main focus is on others, there is an important lesson for individuals as well. Is it dangerous to lie to yourself. If you are doing evil, it is better to acknowledge it, because your thoughts will not be distorted. Who knows? Maybe one day you will repent. But if you rationalize your behavior, then you are in danger of never even being honest enough to realize that you are doing something wrong. That is most dangerous.
Translations Courtesy of Sefaria