The word “mystery” is a confusing translation, as it can mislead the reader of what mystery means and what Paul is talking about. Is it “weird, strange, or an enigma” which is the common interpretation of the word in the English language? No, the word is Greek (μυστήριον ) It means a “secret”–something kept hidden, something previously not revealed. Paul used the term to describe the body of doctrines the risen, ascended, glorified Lord revealed to him. God alone can keep a secret and He had kept these revelations hidden until He chose to disclose them. I believe God waited until Jesus had ascended on High with God our Father and chose Paul as His minister to share this truth of God’s Plan for Mankind. Paul called these doctrines “secrets” for this was what they were. What were these secrets that Peter and the other apostles knew nothing about?