But now is made manifest, and by the scriptures of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith:
Read Chapter 16
Ambrosiaster
AD 400
The mystery which is eternally hidden in God was revealed in the time of Christ, for God is not alone, but from all eternity he has his Word and the Paraclete with him. God decreed that every creature was to be saved by coming to a knowledge of this truth. For the truth of this mystery had been indicated by the prophets in symbols, and it was known only to God…. This wisdom is Jesus Christ, who is from God and was with God forever. Commentary on Paul’s Epistles.
On this ground Pythagoras seems to me to have said that God alone is wise, since also the apostle writes in the Epistle to the Romans, "For the obedience of the faith among all nations, being made known to the only wise God through Jesus Christ; "
By saying this Paul is releasing the weak person from fear. For this secret was contained in the law. Indeed, it is what the law was all about. We cannot ask why it should be disclosed now, for to do this would be to call God to account. We ought not to behave like busybodies but instead be content with what we have been given.