Paul was certainly a Gnostic in his teachings which the church tried to burn and destroy....This secret gnosis emphasized spiritual "resurrection" (i.e,. spiritual rebirth) and physical "resurrection" (i.e., reincarnation) as opposed to a resurrection defined as people sleeping in their graves until it is time their corpses to crawl out of their graves at the last day. Christian Gnostics held the view that if spiritual resurrection was not attained in one lifetime, then the soul would be subjected to as many reincarnations as it takes until spiritual rebirth is attained.
One of the great Church leaders was Clement of Alexandria in Egypt (150-211 A.D.) who indicated that he possessed the secret teaching handed down from the apostles.
In the Gnostic text entitled The Secret Gospel of Mark, one of the Christian Gnostic texts discovered in 1945, describes Jesus performing secret initiation rituals. Before the discovery of this secret gospel, our only knowledge of it came from a letter written by Clement. Clement quotes from this secret gospel and refers to it as, "a more spiritual gospel for the use of those who were being perfected." He also states, "It even yet is most carefully guarded [by the church at Alexandria], being read only to those who are being initiated into the great mysteries." Clement mentions elsewhere that Jesus revealed a secret teaching to those who were "capable of receiving it and being molded by it" He also affirmed that, "The gnosis (secret knowledge) itself is that which has descended by transmission to a few, having been imparted unwritten by the apostles." (Miscell. Book VI, Chapter 7)
The existence of a secret teaching can be found in the New Testament:
“The secret of the kingdom of God has been given to you. But to those on the outside everything is said in parables so that, 'they may be ever seeing but never perceiving, and ever hearing but never understanding…’” (Mark 4:11-12)
"He replied, "The knowledge of the secrets of the kingdom of heaven has been given to you, but not to them. Whoever has will be given more, and he will have an abundance." (Matt. 13:11-12)
"We do, however, speak a message of wisdom among the mature, but not the wisdom of this age or of the rulers of this age, who are coming to nothing. No, we speak of God's secret wisdom, a wisdom that has been hidden and that God destined for our glory before time began." (1 Cor. 2:6-8)
"So then, men ought to regard us as servants of Christ and as those entrusted with the secret things of God." (1 Cor. 4:1)
"At that time Jesus said, "I praise you, Father, Lord of heaven and earth, because you have hidden these things from the wise and learned, and revealed them to little children. Yes, Father, for this was your good pleasure." (Matt. 11:25-26)
Paul wrote about teachings which are taught to spiritual "babies," teachings about righteousness for the more mature, and then teachings for the spiritually mature. Paul reveals this fact immediately after equating Melchizedek to Jesus by stating:
"We have much to say about this, but it is hard to explain because you are slow to learn. In fact, though by this time you ought to be teachers, you need someone to teach you the elementary truths of God's word all over again. You need milk, not solid food! Anyone who lives on milk, being still an infant, is not acquainted with the teaching about righteousness. But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil. (Heb. 5:11-14)According to tradition, after the Roman invasion of Jerusalem, the author of the Gospel of Mark established a church in Alexandria, Egypt. Mark may also have been the author of a "secret gospel" containing more advanced teaching for those being initiated into the Christian mysteries. This secret gospel contains passages portraying Jesus teaching secret doctrines.