The Talmud relates that there was not a prostitute in the world with whom Elazar ben Dordaya did not have relations.
In order to return in teshuva, he had to reach the conclusion that “the matter depends on me alone.
He placed his head between his knees and wept aloud, until his soul departed.”
And what was his rectification? “
A bat kol (Voice from Heaven) was heard proclaiming, ‘Rebbe Elazar b. Dordaya is destined for the life of the World to Come.’”
On this story, R. Yehuda HaNasi said two things:
“R. [Yehuda HaNasi] wept and said: One person may acquire eternal life after many years, while another may acquire it in one hour.
He also said: Not only are penitents accepted, they are even called ‘Rebbe!’”
That Elazar ben Dordaya was forgiven is understandable, but why was he called “Rebbe”?
An explanation, although perhaps not according to the simple meaning, is that a Rebbe is someone who shows the way to others.
Rebbe Elazar ben Dordaya became the Rebbe of a great many people.
He taught that even one who was addicted to sin his entire life can do teshuvah.
Even one who is mired in the depths of sin can set things right.
–Rabbi Adin Steinsaltz