The title "Rabbi" has been likened to the equivalent of a modern title of D.Div (Doctor of Divinity), which includes doctoral studies qualifying one for Th.D (Doctor of Theology) and Ph.D. (Doctor of Philosophy). Jesus called Nicodemus "the teacher of Israel" (John 3:9-10). Compare the modern title and authority of the Chief Rabbinate of Israel.
A rabbi who is held in great esteem and highly respected for his knowledge of Torah and the traditions in the Talmud, and having also earned great honor as a teacher of profound wisdom and insight, and an elder (a man over fifty years of age), is called by the honorific title "Rabbin". Such a man was Rabbin Gamaliel of the first century, the teacher of Saul of Tarsus who became Saint Paul.
The highest spiritual leader of cHasidic Judaism is similarly called "The Rebbe", from the word rabbi, meaning "Master", "Teacher", or "Mentor". Like the title rabbi, rebbe refers to a teacher of Torah or a leader of Judaism, the most influential of whom was the 20th century Rebbe Menachem Mendel Schneerson.
Rabbi Dov Lior, chief rabbi of Kiryat Arba and Hebron, Israel.