It was not through law that Abraham and his offspring received the promise that he would be heir of the world, but through the righteousness that comes by faith (Rom 4:13).

In order for a man to be an heir of God, he must be righteous before God. With sin, no one can be an heir before God, and the promises of blessings given in the Bible are totally irrelevant to the unrighteous according to the Bible.

Do you not know that the wicked will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral nor idolaters nor adulterers nor male prostitutes nor homosexual offenders nor thieves nor the greedy nor drunkards nor slanderers nor swindlers will inherit the kingdom of God (1 Cor 6:9-10).

This principle can be observed in the stories of Genesis that we looked at earlier: for instance, we saw how Adam and Eve were driven out the Garden of Eden when they ate from the tree of the knowledge of good and evil, how Cain became a wanderer when he killed Abel, how all the wicked people died at the time of Noah's flood, and how Ham and his sons, Canaanites, were cursed by Noah after the flood. Thus, the righteousness of God and the eligibility to be an heir of God are inseparable in the Bible. And it is on the basis of this principle that Paul argues in Romans:

What does the Scripture say? "Abraham believed God, and it was credited to him as righteousness (Rom 4:3)."

Again, Paul's interpretation of the story of Abraham in Gen 15 is very unique, and it is worth exploring it.

Then the word of the Lord came to him: "This man will not be your heir, but a son coming from your own body (internal part) will be your heir (Gen 15:4)."

The Hebrew word for "your own body" is me'eh, and it means internal organs or the internal part of being, and thus, the "heir" here refers collectively to the descendants of spiritual birth rather than the biological descendants of Abraham. In other words, those coming from the internal part of Abraham are the ones who believe in their heart and are justified (Rom 10:10)—those that have experienced the spiritual rebirth by believing the reality of the death and resurrection of Jesus Christ.

Therefore, the promise comes by faith, so that it may be by grace and may be guaranteed to all Abraham's offspring—not only to those who are of the law but also to those who are of the faith of Abraham. He is the father of us all (Rom 4:16).

There is no longer the difference between the Jews and the Gentiles. We, believers in Christ, are a chosen people, a royal priesthood, a holy nation, segullah—God's treasured possession, and an excellent people. All the blessings promised to Abraham are ours, and we are a blessing as he was: those who bless us will be blessed through us. The status of humans as heirs of the universe at the beginning of creation has been completely restored in Christ.

… so that, having been justified by his grace, we might become heirs having the hope of eternal life (Titus 3:7).

What is crucial for us, therefore, is that we should stand completely and firmly upon the fact that we have become the righteousness of God through the death and resurrection of Christ. When doubt comes, the sense of guilt comes in, and we stop living as heirs of God: as birds of prey begin to fly over us, we end up being Satan's prey.