The best way to attain full teshuva is through believing completely that one can leave behind his sins and become a new person. The Kedushas Levi (on Megilas Eicha) sees this lesson from the verse (Devarim 10:12): “And now (v’ata) Yisroel, what does Hashem your G-d request of you? Only to fear Him.” The Medrash (Bereishis Rabbah 21:6) states that the word “v’ata” always connotes teshuva.
He explains that we all must believe that Hashem grants new life to a person every second of the day. This is as Chazal say (Bereishis Rabbah 14:9): “’Every neshama must praise Hashem’ (Tehillim 150:6).’ For each and every neshima (breath) that one breathes, he must praise Hashem.” This is because one needs Hashem to grant him new life with every breath that he takes.
Accordingly, when one does teshuva, he must believe that he is no longer the same person that committed the sin. Now that he is a new person, Hashem does not remind him of the sins that his old self did, and he is completely clean from aveiros. If, however, one does not believe this, his teshuva will not help. Thus, the Medrash is saying that “v’ata” refers to teshuva, meaning that if one believes he is “now” (ata) a new person, teshuva will help him.
The Kedushas Levi also uses this idea to explain the pasuk (Eicha 5:21): “Hashem, return us to you and we will return.” The verse continues to say that way we will return to Him is “chadesh yameinu k’kedem” – renew our days as of old. If one believes that he can do teshuva and become a new person, he does, in fact, leave behind his old self and his old aveiros.
