Gnosticism is often seen as part of early Christianity, but the Gnostics and the Christians were diametrically opposed to each other. The Gnostics believed that the God of the Torah was evil, and this was blasphemy to both Christians and Jews. The Christians became hostile to everything associated with Gnosticism.
The Gnostics were dreadfully wrong in their view of YHWH, but they were right about one thing. They recognized that a person contains a physical body and a spiritual body, and there is a struggle between these two bodies. This struggle is the struggle between good and evil. The spirit is good, but the flesh is weak and is influenced by evil spirits. Christians over time became very hostile to the idea of a struggle between spirit and flesh because it was associated with Gnosticism. To this day it is considered heresy.
In this way, the Gnostics served the purpose of distracting Christians away from an understanding that causes many pieces of the Bible to fit together. Christianity may have become hostile to the idea that good versus evil is a struggle within us between spirit and flesh, but if you look back at the words of Christ and the writings of Paul, there is a great deal of text which supports this particular element of Gnosticism.
Christ drew a distinction between a person’s spirit and their flesh and spoke of the spirit as righteous while the flesh was weak.
John 3:5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
John 3:6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
Matthew 26:41 Watch and pray, that ye enter not into temptation: the spirit indeed is willing, but the flesh is weak.
It was the apostle Paul who spoke most frequently about the spirit and the flesh (two parts of one person), but Paul was often speaking of two parts of one person, and not two different people. It is this realization (the Gnostic view) that causes the writings of Paul to make more sense, and to be more consistent with the words of Christ. Here are just a few examples from only one of Paul’s letters.
Romans 8:4 That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
We don’t always walk after the Spirit, but our spirit does.
Romans 8:5 For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.
Romans 8:9 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
Romans 8:10 And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness.
Romans 8:13 For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.
Romans 8:16 The Spirit itself beareth witness with our spirit, that we are the children of God:
Like with the much of Paul’s writings, if it is viewed with an understand that the spirit of the child of God walks after the Spirit, but the flesh of that same child of God walks after the flesh, this understanding changes everything.