When a person sins, that person is in the world of separation
A person sins when that person sees his or herself as a distinct entity - when every element of the universe is separate, and that person's self is severed from the source, from God: this is the "world of separation." Then evil, seen as separate, becomes, in fact, a discrete element of the locality and has the capacity to do harm.
Teshuvah (repentance, return to God) springs from the awareness of universal connectedness and unity with God, which, as opposed to the "world of separation," is the "world of unification." "Teshuvah out of love" is not repentance due to fear of punishment, but from love of God and the desire to find connection with the Eternal.
"There is no evil at all": there is no room for the concept of "evil"; everything is an integral part of the good.
If we look at the universe holistically, as the "world of unification," rather than locally, as the "world of separation," it becomes clear that evil is necessary for the realization of good and in order for that good to reach a higher level. In the holistic view, evil does not exist in and of itself, as it is a necessary element of the overall system. When good overcomes an evil that has been impeding it, the good gains greater worth and deeper understanding; it attains a higher level. That evil, in the universal plan, ceases to be evil. Any evil is evil (and it is indeed evil!) only when it is viewed discretely; looked at holistically, it is a vital component of the good.
One who does teshuvah (repents) out of awe or fear - that person's premeditated sins are rendered as unwitting transgressions. One who does teshuvah out of love - that person's premeditated sins are rendered as merits" (Talmud, Yoma 86b), as, in the final account, these sins provide a reason for repentance and return and, thus, brought about movement to a higher level of spirituality.