The Baal Shem Tov zt’l said he achieved his levels through immersing in the mikvah. We don't have the parah adumah to attain taharah, but we still have the mikvah, which also purifies us immensely.
The Rishonim teach us that mikvah also removes the tumah of aveiros. The Shlah Hakadosh (Shaar HaOsiyos 9, Taharah) writes, "Fortunate is the one who always accustoms himself to have purity. It cleans away all tumos, including the tumah of aveiros."
Or Zarua writes, “In our generation, we can’t punish a murderer. All we can do is not have anything to do with him. We shouldn’t look at him either because Chazal say one may not look at the face of a rasha. He is pasul for all eidus. Even if he killed by accident, we shouldn’t permit him to daven for the amud. Nevertheless, if he does teshuvah, he immediately becomes a perfect tzaddik. Only he needs tevilah to cleanse himself from the aveirah because it made him tamei. Aveiros cause tumah. The Midrash on (Tehillim 51:4) טהרני ומחטאתי מעוני כבסני הרב, 'Cleanse me a lot from my sin, purify me from my iniquity' teaches that whoever commits an aveirah, it is as if he became tamei from a dead person. I learned from Rabbeinu Simchah, ‘All people who want to do teshuvah must go to the mikvah.'
"A story is told in Avos d’Rabi Nosson (3) about a girl captured by gentiles. When she was freed, they brought her to a mikvah because she ate the foods of non-Jews. Non-kosher food doesn’t make a person tamei. Nevertheless, they had her tovel to cleanse her from the aveirah..."
That mikvah purifies us from sins shouldn't surprise us because one of the primary reasons everybody goes to the mikvah on erev Yom Kippur is to purify themselves from aveiros.
The Radvaz (vol.3 415) states, "To do teshuvah for every type of sin, one needs mikvah first."
Rebbe Mordechai of Chernobyl zt’l said, "If someone comes to me without first immersing in the mikvah, I can see all his bad deeds, even those he committed behind closed doors. But if he went to the mikvah before coming to me, I don't see anything bad. The mikvah purifies him" (Raza d'Uvda).
Reb Yosef Chaim Sonnenfeld would immerse himself in the mikvah every day, sometimes even twice daily. Reb Isser Zalman Melzer zt'l asked Reb Yosef Chaim Sonnenfeld zt'l why he goes so often. "Wouldn't it be better to learn Torah at that time?"
Reb Yosef Chaim Sonnenfeld zt'l answered, "If mikvah can turn a goy into a Yid, imagine what it can do to a Yid!" Rebbe Isser Zalman said that Reb Yosef Chaim's response changed his perception of mikvah.
How does mikvah remove aveiros?
The Bnei Yissaschar (Tishrei, 4:11:31) teaches that being in a mikvah is like becoming batel, nonexistent. Indeed, טבל are the same letters of בטל, batel, non-existent. Therefore, when he comes out of the mikvah, he is a brand-new person; he isn't the person who performed the aveiros.
The Bnei Yissaschar writes, "The [four walls of the] mikvah is in the form of a 'ם, the form of a womb. The person immersing in a mikvah is bent over [his head over his chest, and his feet bent up to his torso] in the form of a child in its mother's womb... [In the mikvah, he appears like a child in the womb, and when he comes out] it is like he was newly born. All the days of his past, including the days he sinned, fall away."
The Chinuch (173) writes that the mikvah's waters represent the water at the beginning of creation, covering the earth. When one goes to the mikvah, he should imagine himself going to that place before the creation of man, and when he emerges from the water, he should consider himself newly created.
Stories of Teshuvah and Renewal
Reb Boruch Ber Levovitz zt’l (the Birchas Shmuel) excelled in the mitzvah of kibud av va'em. When his father was ill, he stayed with his father every night. But one night, he couldn’t care for his ailing father, so he asked someone to take his place. That night, his father was niftar. Reb Boruch Ber was brokenhearted. He felt that had he been moser nefesh to care for his father that night, perhaps his father would still be alive.
He traveled to Radin, to the Chofetz Chaim zt'l, to receive chizuk. The Chofetz Chaim zt’l told him, “After you do teshuvah, you aren't the person who sinned. Chazal say, ‘When one does teshuvah, he is like a newborn child.’”
Reb Boruch Ber left the Chofetz Chaim’s home dancing. “I’m a new Boruch Ber! I’m a new person!”
Through the influence of the Magid of Mezritch zt'l, Reb Aharon Gradya zt'l became a baal teshuvah and a great tzaddik. One day, he complained to the Magid that the yetzer hara kept returning to him, enticing him to return to his sinful past.
The Magid told him a mashal: Someone owned a tavern and earned a good living from it. But he was bothered by the rowdy drunkards who patronized his inn. Every night, there were fights, and the furniture in his inn was constantly being broken and needed to be replaced. One day, he decided to close the inn, and in the same place, to open a store that sold fabrics.
The drunks, however, who were used to coming to his tavern, kept returning. They stood at his door, howling for drinks. They even came in the middle of the night.
The fabric store owner would holler from his window, “The bar is closed. This is a fabric store now. The tavern you're looking for doesn’t exist anymore!”
The Magid said, “When the yetzer hara comes to you, tempting you with sins, tell him that he came to the wrong address. You are no longer the Aharon Gradya of your youth. You are a new person, and he should, therefore, go elsewhere.”
As we explained above, mikvah helps us imagine this.
