Here is the earliest indication of Gnosticism as a religion—or at least a philosophy, a way of life that eventually became a religion—having an impact on the Christian church. Gnosticism was mystical and charismatic, not rational. Rational means "relating to, based upon, or agreeable to reason." Mystical means "having a spiritual meaning or reality that is neither apparent to the senses nor obvious to the intelligence." Gnosticism was ascetic and exclusivist, and it relied heavily on magic.
When these elements are combined with Jewish zeal, a religion was created that undoubtedly appealed to a large segment of the Christian church. Paul goes on to show in the book of Galatians that the primary racial group in the foreground of the book of Galatians are not Gentiles. They were Jews who were practicing Halakah, but who had been heavily influenced by Gnosticism, having made it part of their worship routine, that is, a part of their lives.
John W. Ritenbaugh
The Covenants, Grace, and Law (Part 26)