The Mystery of Israel's Future.
Romans 11:25-26 a. It may save Gentile believers from a dangerous self-conceit (cf. Romans 12:16) to learn the secret that the hardening (see Romans 11:7) which has partially befallen Israel (the remnant is exempt; Romans 11:5; Romans 11:7), will last only until the full complement of the nations enters into God's kingdom; then all Israel will be saved. A mystery is a secret truth concerning God's kingdom made known by express revelation; cf. Romans 16:25; Ephesians 1:9 * Ephesians 3:3 ff., Matthew 13:11, etc.
Romans 11:26 b, Romans 11:27. The event is described in words blended from two passages of Isaiah, signifying chiefly two things: Israel's Saviour comes of Israel (cf. Romans 9:5); and His salvation lies in the removal of Israel's sin (cf. Romans 4:7 f., Matthew 1:21; Hebrews 10:15-18).
Romans 11:28 f. The mass of the Jews are, in God's eyes, at once enemies and beloved: enemies, since they oppose the giving of the gospel to Gentiles (1 Thessalonians 2:14-16, etc.); beloved for their fathers'sake, in whom God chose the nation. That election stands good; acting in sure foresight (cf. Romans 8:29 *), God never regrets His grace-gifts, etc.
Romans 11:30-32 marks out the line of vindication. You and they have both proved disobedient to God (for the former, see Romans 1:20-23; for the latter, Romans 10:21, etc.). He has used each set of rebels to overcome the others: just as you were aforetime disobedient, and now by reason of their disobedience have become objects of mercy (cf. Romans 11:12; Romans 11:15), so they now have fallen into disobedience by reason of the mercy shown to you, that finally mercy may be shown to them too. Universal disobedience ends in universal mercy! Shut up unto disobedience (cf. Galatians 3:22) means the precluding of every other issue; all (not every man) signifies Jews and Gentiles as a whole: Paul is dealing with broad historical issues. The difficulty of Romans 1:24; Romans 5:20; Romans 9:18 recurs, viz. that God should take measures to aggravate sin. But downright, unmistakable disobedience clears the moral atmosphere; brought to a crisis, the fever is curable.
Romans 11:33. The apostle's sorrow (Romans 9:1) is turned to rapture as he contemplates the unfolding of God's world-plan: O the depth of the riches and the wisdom and the knowledge of God! (mg.). His wealth is the infinitude of His resources His wisdom lies in the skill of His methods; His knowledge, in the mastery of all the facts and conditions! The beholder is lost in these depths and mazes! (cf. Romans 8:38 f.). The sayings of Romans 11:34 f. (drawn from Isaiah, Job, and Jeremiah) impressively reflect upon the mystery of God's dealings with human life, in which He needs no creaturely counsel or aid.
Romans 11:36. Alike transcendent and immanent, God is the source (see 1 Corinthians 8:6), the operative Agent (1 Corinthians 12:6), the final issue of the being of mankind.