Because you are sons, God sent the Spirit of his Son into our hearts, the Spirit who calls out, "Abba, Father." So you are no longer a slave, but a son; and since you are a son, God has made you also an heir (vv. 6-7).

To all those who have believed in Jesus Christ are given the right to become the sons of God, who are also the heirs of God and co-heirs with Christ. But we should not forget that God is a good God for both his sons and those who are not his sons yet.

But I tell you: Love your enemies and pray for those who persecute you, that you may be sons of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous (Mat 5:44-45).

Where, then, is the difference between God’s children and those who are not God’s children? This is a good question. In order to get the answer to this question, we will go to the stories of Abraham. The stories begin with the genealogy of Terah, the father of Abram in chapter 11 of Genesis.

This is the account of Terah. Terah became the father of Abram, Nahor and Haran. And Haran became the father of Lot. … Abram and Nahor both married. The name of Abram's wife was Sarai, and … Now Sarai was barren; she had no children (Gen 11:27-30).

Think why genealogies are so important in the Bible. Abraham had many servants living with him, but had no children, and his wife was barren, which meant the end of the genealogy. Then, God said to him:

Leave your country, your people and your father's household

and go to the land I will show you.

I will make you into a great nation and I will bless you;

I will make your name great, and be a blessing.

I will bless those who bless you, and whoever curses you I will curse;

and all peoples on earth will be blessed through you (12:1-3).

These promises of blessings can be summarized in the following points:

1. The Land will be given to him and his descendants.

2. His descendants will become a great nation.

3. He himself becomes a blessing.

4. All peoples on earth will be blessed through him

These points will help us understand the underlying messages of the whole book of Genesis, as well as those of the books like Exodus, Numbers, Joshua, or even the gospels in the New Testament. The kinds of blessings Abraham received are so extraordinary that they go beyond our common sense or even moral sense, which is especially true concerning the promise, “I will bless hose who bless you, and whoever curses you I will curse.”

He treated Abram well for her sake, and Abram acquired sheep and cattle, male and female donkeys, menservants and maidservants, and camels. But the Lord inflicted serious diseases on Pharaoh and his household because of Abram's wife Sarai (12:16-17).