You must be in fellowship prior to your Bible study, so that the spiritual information you receive can become a source, of blessing to your soul and produce spiritual growth.
3 How that
[hoti] by[kata] revelation[apokalupsis] he made known[gnorizo]
unto me[moi] the mystery;[musterion] (as[kathos] I wrote afore[prographo] in[en] few words,[oligos] KJV-Interlinear
3 that by
revelation there was made known to me the mystery, as I wrote before in brief. NASB
Paul was educated within the Jewish educational system. He also received training from within the Roman system of education. His scriptural knowledge likewise came from the scriptures, but here he mentions another source of knowledge, and that is knowledge received direct from God. Knowledge revealed directly from God to him.
The mystery, herein referred to has many components. But primarily this is in reference to the change in the emphasis and presentation of the gospel and the scriptures, not from Jewish sources, but now from gentile sources.
Throughout the Old Testament, the source of doctrine was held in the custody of the Jewish people. But due to their failure in disseminating the scriptures to the world, and their attempt to keep it all to themselves, and furthermore, because of their drifting far, far away from the true principles taught in the scriptures, then they not only lost that custodial privilege after they rejected the Messiah, of whom the scriptures were written, but they also lost their whole way of life within the celebrated feasts and sacrifices.
As to the prior text that Paul had written and now refers to, nothing further is mentioned to identify that prior writing. Most commentaries merely speculate as to that source.
Even verse two alludes to prior knowledge that both Paul and his readers already possessed.
And even though Paul wrote the majority of the books that are included in our New Testament, it is most likely that he wrote many other letters, that did not make it into the Bible, and probably have been lost to history.
In any case, knowledge of these things did not begin with Pauls writing, but had already existed long before Paul and others had begun writing the New Testament as we know it today.
What is important in this verse, is that knowledge already existed for people to learn and know about, prior to the writing of these books, and that the knowledge that was written or revealed, did not come from man, but came from God.
Therefore these subjects are not the product of human invention, but of divine revelation.
