Abraham received the promise because of his faith in the Lord.   That promise had a physical component involving Abraham being the progenitor of Christ Jesus.   

However, the promise was based on Abraham`s faith and the Lord`s faithfulness.   It was not based on his genetic superiority.   

Hence, the blessings that followed from Abraham to his descendants was based on their faith in the Lord and not their genes.   

The evidence of this is throughout the Bible.   The Jews were not blessed regardless of their attitude toward the Lord.   When they turned their faces to the Lord, they were blessed.   When the turned their faces from the Lord, they suffered.   

God is a Spirit.   He is the Holy Spirit.   He created man as a spirit with a soul and a body.   In Christ Jesus He made Himself a body with a soul.   

Our Lord has declared this:

But without faith it is impossible to please him: for he that comes to the Lord must believe that he is, and that he is a rewarder of them that diligently seek him. Heb 11:6 Believe that    → Jesus is Mighty God    → Jesus is loving and giving    → Jesus will reveal Himself to those who seek Him    → Jesus Himself is your exceeding great reward Gen 15:1 Joh 17:3 Faith is the power to appropriate what Grace has provided.     It pleases the Lord Jesus for us to receive what He has made available to us.     2Co 8:9

Furthermore, He said this about the flesh:

It is the spirit that quickens; the flesh profits nothing: the words that I speak unto you, they are spirit, and they are life. Joh 6:63 This is profound Truth!         → The Holy Spirit makes us alive and keeps us alive.         → The flesh does not help anything.         → It is sustained by the Spirit.         → Our life comes by the Word Of The Lord through His Holy Spirit.      But, the Holy Spirit waits for us to release His power.      We do so by faith in the authority of Christ and His Word and courage to operate as Sons Of The Holy Spirit.

A major implication of our Lord`s demand for faith in Him and His disdain for the flesh is that no one is chosen because of their flesh, their DNA.   

Who then are the Chosen People if it is not the physical descendants of Abraham?   

For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: Rom 2:28 Acceptance by the Holy Spirit is only through the beloved, Christ Jesus.     race, ethnicity, gender and nationality are irrelevant to the Holy Spirit.

The person who spoke these words was a descendant of Abraham.   But, more importantly, he had received the revelation of Truth In Christ Jesus and understood the Old Testament scriptures.   

Know you therefore that they which are of faith, the same are the children of Abraham. Gal 3:7 Forget genetics and bloodline.     It is about faith in the finished work of Christ Jesus.

Our Lord is not a respecter of persons.   He honors His promises in every case, but we must make sure that we understand to whom the promise is given and the requirements associated with the promise.   

Then Peter opened his mouth, and said, Of a truth I perceive that the Lord is no respecter of persons: Act 10:34 To be a respecter of persons implies that one is unjust.     It is impossible for the Lord to be unjust.     He is holy and perfect in all His ways.      The concept of Chosen People is perverse.     Abraham believed the Lord and the Lord rewarded His faith with a promise that His seed would be blessed.     And that one particular seed would bless all the nations of the earth.     That seed is Christ Jesus.      Hebrews are blessed as long as they operate in faith, just as gentiles.

But in every nation he that fears him, and works righteousness, is accepted with him. Act 10:35 This is an important statement regarding the universal nature of the New Covenant.     It is with all mankind - whosoever will come.     Rev 22:17

And be found in him, not having my own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of His Holy Spirit by faith: Phi 3:9 When we are In Christ we are clothed with His righteousness by the Faith Of Christ.      This is the essence of the Gospel of Grace Through Faith.      It diminishes our performance and elevates the performance of Christ Jesus on our behalf.     The result is that our performance becomes the performance of the Holy Spirit through us.

For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith. Rom 4:13 The promise was before the Law was given and is eternal because it was based on faith.     Whereas the Mosaic Covenant was based on performance and was not eternal.     In Christ Jesus the Mosaic Covenant was consumated and replaced by the New Covenant of righteousness by Grace Through Faith In Christ Jesus.

None of us are qualified because of our DNA and none of us are disqualified by our DNA.   

There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for you are all one in Christ Jesus. Gal 3:28 We are not all Water Baptized the same and some believers have never been Water Baptized.     However, it is in the putting on of Christ Jesus that we are baptized into Him.      There is no difference in us who are In Christ.      This statement is the broadest most inclusive statement that can be made regarding our Lord's will for humanity.     We are not one in physical birth but we become one in the New Birth.

The Chosen People are those who respond positively to the Gospel of Jesus Christ.   The set of all such people constitute the Body Of Christ.   

For many are called, but few are chosen. Mat 22:14 We are all called.     The chosen are those who appreciate the call and respond to it by receiving Christ Jesus as Lord and Saviour.     Such are clothed with His Holy Spirit.         → We are chosen by being clothed with His Holy Spirit.         → Those who reject Christ Jesus are rejected by Him.     Act 2:21 Joh 1:12 Rev 20:15

The following verse is misunderstood to speak to Spirit Salvation.   As is the case with Soul Salvation, Physical Salvation is a different than Spirit Salvation.   

And so all Israel shall be saved: as it is written, There shall come out of Zion the Deliverer, and shall turn away ungodliness from Jacob: Rom 11:26 'All Israel'?     This must be in reference to spiritual Israel.      Only believers In Christ Jesus will be saved spiritually.      It is possible that this is speaking to the nation of Israel that exists today being physically saved by Christ Jesus at His return.      Spritual salvation requires the New Birth which only happens as a result of faith    → that Jesus is Mighty God and Savour,    → that He shed His blood for our forgiveness,    → that He bore stripes for our healing,    → that He raised Himself from the dead and    → that He gives His Holy Spirit to whosover asks.