Know and understand that it is [really] the people [who live] by faith who are [the true] sons of Abraham. Galatians 3:7(AMPC)
When the Jews told Jesus that they were children of Abraham He disagreed saying if they truly were Abraham’s children then they would do what Abraham did which is believe in Him (Jesus) because Abraham believed.
John 8:39.
A true son of Abraham isn’t necessarily the one of his flesh and blood but the one who believes God just even as Abraham believed. Like Abraham, the true son or daughter believes the God who raises the dead and calls things that are not as though they were. Romans 4:17. The true son of Abraham is defined as.. “Blessed are those who have not seen and yet have believed.”John 20:29
Now this pleases God and He credits it to us as Righteousness or right standing with Him. Choose to believe the unseen God, choose to believe His Salvation through His Son who died and rose from the dead. Then you’re a true son and daughter of Abraham, pleasing to God and abundantly blessed.