Matthew 23:8

You must not be called Teacher.' [Rabbi in the Hebrew language.] About the same as Doctor of Divinity. Jesus rebukes all who use religion as a means of gaining glory for themselves. This sin of "showing off' [ostentation] was the root of the Pharisees' other sins. The teachers of the Law did not allow their students to call them by name. They could only be spoken to as "Teacher." Alford (Greek Testament) gives this warning: "To understand and follow such commands [as Christ gives in these verses. RDI] in the slavery of the letter, is to fall into the very Pharisaism against which our Lord is uttering the caution." All brothers of one another. All in Christ stand equal to each other [even though they may have different duties]. Have only one Teacher. CHRIST [through the Holy Spirit (Acts 1:1-2)].