Were the things in Paul's epistles ever revealed before in God's dealings with mankind?
No. The revelations given through Paul's epistles had never been disclosed in any previous dealing of God with mankind. They cannot be found in the Old Testament, Christ's earthly ministry, or the early parts of Acts. God had kept them secret since the beginning of human history, or even before.
Les teaches that the truths found in Paul's epistles were never revealed previously in any of God's dealings with mankind. He points out that many of Paul's doctrines cannot be found in the Old Testament, in Christ's earthly ministry, or in the early parts of Acts. Instead, they were revelations God had kept secret since the beginning of human history, or even before. Les also suggests a useful study: take a concordance and look up the word 'mystery' wherever it appears in Paul's epistles, then gather the concepts Paul associates with that revelation. He connects this to Deuteronomy 29:29, where the secret things belong unto the Lord our God, because He is sovereign and Creator of everything.