Here’s (vv. 2-13) perhaps the longest parenthetical in the Bible. Twelve verses long, bookended by “for this reason.” This digression leads us into some significant spiritual truths.
At the time, the inclusion of the Gentiles in God’s plan was big news, as it was not obvious in scripture to that point. It was Paul’s job, by God’s grace, to divulge this mystery, this good news, which the apostles and prophets revealed (v. 5), to the Gentiles.
When Paul returns to his script, he will give credence to all that we as Christians possess at our fingertips, for starters, “boldness and confident access through faith” (v. 12), and end with a powerful doxology. “Now unto him who is able… .” (vv. 20-21)
Look for a moment at the “according to’s” in Chapter 3 (7, 11, 16, 20), certainly a sermon on their own. Paul acted, and we act, accordingly to the gift of God’s grace, the working of his power, without and within, his eternal purpose, and the riches of God’s glory.
In what you do, are you relying on his grace, requiring his power, refering to his eternal purpose for you, and revering his glory? These are the requisites for success.