Gnosis (from the Greek word for knowledge) is not limited to one time and place. Gnosis is the spiritual heart of every religion. This is why every great adept teaches the same message, that there is one way to know the Divine, and it is timeless and eternal.

Whenever the Law declines and the purpose of life is forgotten, I manifest myself on earth. I am born in every age to protect the good, to destroy evil, and to re-establish the Law. - Hinduism. Krishna in the Bhagavad Gita 4.7-8

Think not that I have come to abolish the law and the prophets; I have not come to abolish them but to fulfil them. For truly, I say to you, till heaven and earth pass away, not an iota, not a dot, will pass from the law until all is accomplished. - Christianity. Jesus in the Bible, Matthew 5.17-18

Lo! We inspired you [O Muhammad] as We inspired Noah and the prophets after him, as We inspired Abraham and Ishmael and Isaac and Jacob and the tribes, and Jesus and Job and Jonah and Aaron and Solomon, and as we imparted unto David the Psalms; and messengers We have mentioned to you before and messengers We have not mentioned to you... messengers of good cheer and of warning, in order that mankind might have no argument against God after the messengers. God was ever Mighty, Wise. - Islam. Qur'an 4.163-65

Naught is said unto you [Muhammad] save what was said unto the messengers before you. - Islam. Qur'an 41.43

I have seen an ancient Path, an ancient road traversed by the rightly enlightened ones of former times. - Buddhism. Samyutta Nikaya ii.106

The Master said, "I have transmitted what was taught to me without making up anything of my own. I have been faithful to and loved the Ancients." - Confucianism. Analects 7.1

Therefore, the students and instructors of Gnosis come from every religion and seek to perfect their own religion within themselves.