Why are you (still) a Christian?

[Bucky Ball]

Rabbinic Judaism emerged after the Jewish-Roman War, so naturally the title of Rabbi will not be found in the Hebrew scriptures.  It'd be like looking for "Pope" in the New Testament.

Yes, and I wouldn't pay any more attention to a Rabbi than I would the Pope.

Your problem is you pay no attention to anyone. 
You consider yourself the expert on everything. 

Jesus was sometimes called “rabbi” in the Gospels (Matthew 26:25, 49; Mark 9:5, 11:21, 14:45; John 1:38, 49, 2:2, 4:31, 6:25, 9:2, 11:8). The word “rabbi,” as John informs us, is translated “teacher” (John 1:38). The title “teacher” is more common.

A rabbi (/ˈræbaɪ/) is a spiritual leader or religious teacher in Judaism.[1] One becomes a rabbi by being ordained by another rabbi—known as semikha—following a course of study of Jewish history and texts such as the Talmud. The basic form of the rabbi developed in the Pharisaic (167 BCE–73 CE) and Talmudic (70–640 CE) eras, when learned teachers assembled to codify Judaism's written and oral laws. The title "rabbi" was first used in the first century CE. In more recent centuries, the duties of a rabbi became increasingly influenced by the duties of the Protestant Christian minister, hence the title "pulpit rabbis", and in 19th-century Germany and the United States rabbinic activities including sermons, pastoral counseling, and representing the community to the outside, all increased in importance.