Its catechism is of the Seventh School of Indian philosophy, precursor of the Eclectic School of Theosophy, revived in the 3rd century CE by Ammonius Saccas.
Ammonius Saccas was the Alexandrian Socrates of Neo-Platonism and teacher of Plotinus.
But the real author of the Bhagavad Gita is Krishna-Christos, the “still small voice.”