I think we are on the same page there. After Alexander the Great, the western world including parts of the Middle East was very much Hellenized and Hellenistic and Indian culture obviously intersected or overlapped to some extent as shown by Indian temple art and astronomy/astrology.
In any case, a cursory overview reveals a large number of parallels (the list is incomplete and provisional and possibly not entirely accurate on one or two points):
The tripartite composition of the soul.
The concept of a higher and lower self, one divine and one human.
Union of the human soul with God as the ultimate goal of life.
Five elements (earth, water, fire, air and ether) that constitute the universe.
Five sensory faculties: sight, smell, taste, hearing and touch.
The concept of cosmic creation by a process of emanation Greek απόρροια aporrhoia from the highest spiritual principle (God/the One).
Triadic cycle of abiding-procession-return, Greek μονή mone, πρόοδος proodos, επιστροφή epistrophe
Impermanence or “illusory” nature of the physical world.
The concept of the “heart” as the innermost core of the self, Greek καρδιά kardia, Sanskrit हृद् hRd and its role in attaining enlightenment or salvation.
Salvation through a process of psychic/spiritual purification, illumination and deification culminating in unity with God.
Prayer, meditation and contemplation as a means of attaining enlightenment/salvation.
Magical/spiritual formulas or “mantras” as an aid to invocation, concentration, interiorisation of consciousness, etc.
Remembrance or recognition of God.
Observance of certain moral and ethical precepts.
Set of obstacles encountered on the path that are to be overcome.
Renunciation of or indifference to material things as an aid to spiritual advancement.
The concept of “divine grace”, Greek χάρις haris, Sanskrit शक्तिपात shaktipāta and its role in spiritual salvation.
Supernatural powers or divine gifts Greek χαρίσματα charismata Sanskrit सिद्धि siddhi accomplishments, as a manifestation of divine grace and spiritual advancement.
The role of a spiritual teacher or master as a guide on the path.
Reincarnation or metempsychosis, etc., etc.
I’m fully aware that there is a difference between parallels and diffusion. But if we can establish a number of parallels beyond what can reasonably be regarded as “coincidence” or "multiple discovery", then I think we have good reason to at least try to look into the problem of diffusion or origin.