Paul is telling the Jews that they should be aware of a mystery that will last until the time of the Gentiles has come. The Israelites hearts will be hardened until this time.
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25. Mystery [NKJV]. “This word is used to refer to NT [New Testament} truth previous not revealed (Ephesians 3:2-6). This mystery has two components: (1) Israel has experienced a partial spiritual hardening, and (2) that hardening will last only for a divinely specified period of time. (MacArthur, John, The MacArthur Bible Commentary. [Nashville, Thomas Nelson Inc., 2005], 1543)
“A great deal has been written about the word ‘mystery,’ whose Greek equivalent occurs in one setting only in the Synoptics (Mark 4:11), not at all in John’s Gospel, but some twenty times in Paul’s writing.” (Mounce, Robert H, The New American Commentary, Volume 27, Romans. [Broadman & Holman Publishers, 1995], 223)
“Paul used the word in reference to something that was formerly hidden but now is revealed by God so that all may understand. In the present context the mystery referred to ‘God’s saving activity toward Israel.” (Mounce, 224)
“The hardening that Israel had experienced was limited in scope and in time. It was ‘in part’ in that some (the believing remnant) had not become callous toward God.” (Mounce, 224)
26. All Israel [NKJV]. “All the elect Jewish people alive at the end of the Tribulation, not the believing remnant of Jews with the church during this church age.” (MacArthur, 1544)
“It is the nation he has before us in this chapter. In every age, only a remnant is saved.” (McGee, J. Vernon, Thru the Bible: Volume IV. [Nashville: Thomas Nelson, 1983], 725)
27. “Paul was saying that beyond the current period of Israel’s unbelief there would come a time when believing Jews would turn to Christ in faith.” (Mounce, 225)
28. “The Jewish people are ‘enemies’ to the believing Gentiles because of their hostile attitude toward the gospel. But to God, the Jewish people are ‘beloved for their fathers’ sakes.’ God will not break His covenant with Abraham, Isaac, and Jacob.” (Wiersbe, Warren W, The Bible Exposition Commentary New Testament Volume 1 Matthew-Galatians. [Colorado Springs: David C Cook, 2004], 552)
29. I like the Good News Bible for this verse. (v. 29 GNT)
“God will be consistent with Himself and true to His Word no matter what men may do.” (Wiersbe, 552)
30-31. “God will extend His grace to unbelieving Israel, just as He did to unbelieving Gentiles (cf. Romans 5:8). Salvation, whether of Jews or Gentiles, flows from God’s mercy (cf. 1 Timothy 1:12-14).” (MacArthur, 1544)
“Mercy was extended to the Gentiles because of Israel’s disobedience. Mercy would be extended to Israel because of the mercy shown to the Gentiles.” (Mounce, 226)
32. “Though not the author of sin (Psalm 5:4; Habakkuk 1:13; James 1:13). God allowed man to pursue his sinful inclination so that He could receive glory by demonstrating His grace and mercy to disobedient sinners (cf. Ephesians 2:2; 5:6)
33-36. “The majesty, grandeur, and wisdom of God’s plan revealed in verses 1-32 causes Paul to burst out in praise.” (MacArthur, 1544)
33. “The difficulty is with our inability to comprehend the wisdom and ways of God.” (McGee, 727)
34. “No one knows the mind of the Lord—that’s the answer. It was Paul’s ambition to know Him.” (McGee, 727) (Philippians 3:10; Isaiah 40:13)
35. “Have you ever really given anything to God which put Him in the awkward position of owing you something? If you were able to give God something, He would owe you something. What do you have that He hasn’t already given you?” (McGee, 727)
He has given us everything, some give back to Him, in praise to Him.
36. “See 1 Corinthians 8:6; 15:28; Ephesians 1:23; 4:6; Hebrews 2:10. God is the source, the sustainer, and the rightful end of everything that exists.” (MacArthur, 1544)
Amplified Bible (AMP)
Copyright © 2015 by The Lockman Foundation, La Habra, CA 90631. All rights reserved.
Holman Christian Standard Bible (HCSB)
Copyright © 1999, 2000, 2002, 2003, 2009 by Holman Bible Publishers, Nashville Tennessee. All rights reserved.
New King James Version (NKJV)
Scripture taken from the New King James Version®. Copyright © 1982 by Thomas Nelson. Used by permission. All rights reserved.
In this article Scripture quotations taken from KJV.
McGee, J. Vernon, Thru the Bible: Volume IV. Nashville: Thomas Nelson, 1983
MacArthur, John, The MacArthur Bible Commentary. Nashville, Thomas Nelson Inc., 2005
Mounce, Robert H, The New American Commentary, Volume 27, Romans. Broadman & Holman Publishers, 1995
Wiersbe, Warren W, The Bible Exposition Commentary New Testament Volume 1 Matthew-Galatians. Colorado Springs: David C Cook, 2004