God has never and will never reject His people. His faithfulness is the foundation of our faith. Despite their sin and unfaithfulness, He remains faithful. If God could reject Israel as a people and as a nation, there would be no rational reason for Christians to trust Him or His word. Therefore it is appropriate that we pray His promises, not as a reminder to Him, but to ourselves!
Hosea 1:1: When Israel was a child, I loved him, and out of Egypt I called My son.
Jeremiah 31:1-3: Thus says the Lord:
“The people who survived the sword Found grace in the wilderness— Israel, when I went to give him rest.” The Lord has appeared of old to me, saying: “Yes, I have loved you with an everlasting love; therefore with lovingkindness I have drawn you.