Why do church not know John the Baptiser's first appearance on earth was as Zarathustra, so well qualified

Question

In Zechariah 6 v 12
It talks about the 2 Messiahs one a Priest one a King

Behold, the man whose name is the Branch: for he shall branch out from his place, and he shall build the temple of the LORD. 13 It is he who shall build the temple of the LORD and shall bear royal honor, and shall sit and rule on his throne. And there shall be a priest on his throne, and the counsel of peace shall be between them both."'
In ' The Testament of the 12 Patriarchs ..it says
'For The Lord will raise up from levi someone as high priest, and from Judah someone as King.
Patriarch Judah himself declares...' For to me The Lord gave the Kingship, and to him the priesthood, and he set the the kingship under the priesthood '
http://www.thecosmicenergyexperience.com/hehpsehboah_on_earth_before.htm

Answer 1

Jesus was both Messiah, priest and king. John the Baptist was the cousin of Jesus, it is well documented in the Bible that he leaped in his mother's womb at the sound of Jesus' mother's voice.