Note 16 at Eph. 1:9: The Greek scholar A.T. Robinson says the Greek word MUSTERION, which was translated "mystery" here, means "something that could not be known by men except by divine revelation, but that, though once hidden, has now been revealed in Christ and is to be proclaimed so that all who have ears may hear it" (Handbook to Ephesians, p. 19).

The specific mystery that Paul is speaking about is explained in the next verse (v. 10). The truths of God are mysterious only to those who do not soften their heart (see note 3 at Mk. 8:17, p. 258) by seeking God with their whole heart. As Jeremiah 29:13 says, "And ye shall seek me, and find me, when ye shall search for me with all your heart."

The truths of God are hidden for His children, not from them (see note 1 at Mt. 13:11, p. 191). The Holy Spirit has been instructed to teach us all things (Jn. 14:26) and has given us an unction so that we know all things (1 Jn. 2:20). We only have to appropriate what is ours (see note 6 at 1 Cor. 2:16, p. 870).