The most secretive and troubling knowledge that Jesus would try to teach his disciples was who his Heavenly Father actually was and the major differences between the arrogant good and evil creator god of this world, Yaldabaoth/Yahweh and his actual Father the divine pure invisible spirit, God the Mother/Father, the Emanator of All.
The Christ/Logos wasn't created by his Heavenly Father, he was "Begotten" and "Emanated" out of the Heavenly Father.
Jesus didn't teach this openly to his followers except for Thomas, his twin brother, but he did entrust this knowledge to his most trusted disciple John after his resurrection.
Here's a few portions from the "Secret book of John" where Jesus explains this to John, his most beloved and trusted disciple.
