For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
n.l. pearson
The "mystery" really isn't one to us whom believe: 1 Timothy 3:16 says
"Beyond all question, the mystery from which true godliness springs is great: He appeared in the flesh, was vindicated by the Spirit, was seen by angels, was preached among the nations, was believed on in the world, was taken up in glory."
Also, another easy scripture to understand is Colossians 2:2; in it Paul says " My goal is that they may be encouraged in heart and united in love, so that they may have the full riches of complete understanding, in order that they may know the mystery of God, namely, Christ."
Singapore Moses
Rom. 16:25 says, "Now to him that is of power to establish you according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began."
► Lets analyze what the Apostle Paul meant by the "mystery" in the above verse:
✿ This is certainly a second postscript.
✿ Some think that Paul added it when he got to Rome and after he had written Ephesians concerning the mystery that had been kept secret from ages past (Eph. 3).
✿ It is in all the MSS but two or three. Some have it after Rom. 14:23 and others have it here Rom. 16:25. Some have it in both places, but there is no question of its genuineness and authenticity