How long has God's mystery been kept hidden?
God’s mystery, or secret, was kept hidden since before anything was ever created. It remained totally secret in the mind of God and was not preached by Jesus or Peter. Only after the cross and resurrection was it revealed, now given through the Apostle Paul for the Church.
The mystery or secret was kept secret since before anything was ever created, and God kept all of it hidden in His own mind. That is why Jesus could not preach it and Peter could not preach it, because it was still totally secret. But because the price of redemption was accomplished, the work of the cross is done, and because of the power of His resurrection, God can now pour out the whole package of revealed truth. That package comes from the pen of the Apostle Paul and contains all the truth the Church needs today. We are not to throw away the rest of the Bible, but Christendom would see things happen if it spent 90% of its time in Paul’s epistles and 10% in the rest of the Bible.
Now to him that is of power to stablish 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,