God's promises are secure because they depend on Him, not us.

Paul shifts to a heavy and honest topic: Israel's rejection of Christ. He begins with deep grief. These are his people and many have not received the gospel.

Did God's promises fail? No.

He explains that not everyone who is physically descended from Israel is part of the true people of God. In other words, God's promise has always been based n His calling, not human effort or lineage. 

God's faithfulness is not dependent on human response. Even when people reject Him, His plan is still unfolding. 

Reflection ?: Where are you tempted to question God's faithfulness based on what you see?

Dig Deeper: What does this passage teach about the difference between human expectation and God's purpose?