As a matter of fact he wasn’t, he was a Jew.
He didn’t believe in his own divinity? He didn’t believe in his resurrection? Tell me what part of the Apostles’ Creed and the Nicene Creed Jesus didn’t believe in! (Yes, I know they weren’t written yet.)
Not of the Rabbinic type, if you speak of the religion versus the ethnicity.
At one time, the Christians were known as “Nazarenes” after what was spoken (not written) of by the prophets of Jesus, per Matthew 2:23. The term is used in a derisive manner by Tertullus in Acts 24:5 to describe Christians.