The Bible says Christ's people are the children of Abraham.
Not any more. Israel fell.
Romans 11
11 I say then, have they stumbled that they should fall? Certainly not! But through their fall, to provoke them to jealousy, salvation has come to the Gentiles.
"Their" refers to the children of Abraham whom God called Israel. Paul explains the gift to them who benefited from the fall.
Ephesians 2
11 Therefore remember that you, once Gentiles in the flesh—who are called Uncircumcision by what is called the Circumcision made in the flesh by hands— 12 that at that time you were without Christ, being aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope and without God in the world. 13 But now in Christ Jesus you who once were far off have been brought near by the blood of Christ.