Abraham Had Two Sons
"For it is written, that Abraham had two sons, the one by a bondmaid, the other by a freewoman. But he who was of the bondwoman was born after the flesh; but he of the freewoman was by promise. Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar. For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children. But Jerusalem which is above is free, which is the mother of us all. For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband. Now we, brethren, as Isaac was, are the children of promise. But as then he that was born after the flesh persecuted him that was born after the Spirit, even so it is now. Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman. So then, brethren, we are not children of the bondwoman, but of the free." Galatians 4:22-31
Abraham had two sons. He had one son by Hagar the Egyptian, who was his wife's slave, whose name was Ishmael. He had another son, by his wife Sarah, who God promised he would give him. This son's name was Isaac. Hagar represents Mount Sinai, which answers to Jerusalem, and is in bondage with her children. Ishmael represents the law and commandments which, in a sense, was born at Mt. Sinai.
This Mount Sinai is where Moses received the Ten Commandments from God to teach Israel. The law is the Old Covenant and was meant to teach us about sin and bring us unto Christ. The law is spiritual but is weak through the flesh. The law promotes self righteousness and getting to heaven without God. The law was bondage for the Israelites because they made it an idol and started trusting in it more than God.
For by the law is the knowledge of sin. Now Sarah is compared to Mount Zion and New Jerusalem, which is in heaven, and is free. Isaac represents the New Covenant and the Spirit, and was born from up above at Mount Zion. The difference in these two covenants is that one is of faith and one is of works. Sarah represents faith and God is married to faith. Hagar represents works of the flesh, and God is not married to that which is not of faith.
For it is impossible to please God without faith and it is written that the just shall live by faith. She that has a husband has less children than she that does not. Remember when Moses sent out the spies to check out the promised land, only Joshua and Caleb came back with a faith report. The rest of the spies came back with an evil report. Those who came back with an evil report were trusting in their own strength and said they saw giants and appeared in their own site as grasshoppers. There is less children of faith than there is of self righteousness.
Abraham was given a promise by God that he would receive land and a seed. The seed that he would receive was Jesus Christ. God told Abraham that his family would bring forth the Messiah. Abraham believed God and it was accounted to him for righteousness. The promise was not just to Abraham alone but to all those of faith in the Lord Jesus Christ. That is why God said, "In Thee Shall All Nations Be Blessed."
He promised Abraham that he would bring forth the Christ and he promised us that if we believe that Jesus came, died for our sins, and rose again on the third day... we would receive the promise of the Spirit and eternal life. Now when God told Abraham this; he and his wife Sarah were very old. Sarah was past the child bearing age and received Isaac by the Spirit of God. She judged him faithful that promised.
Isaac was born by promise after the Spirit. This was a miracle. Now Abraham, while waiting on God, starting leaning to his own understanding and had a baby by Sarah's bondmaid Hagar. That is why the scripture says that Ishmael was born after the flesh. Abraham was trusting in the flesh, and that Hagar was young enough to bear children, and thought he would help God out by bringing the promise to fruition on his own.
That is what people who follow the Ten Commandments do, instead of trusting in the promise of God by faith. That is why the law is of works and not faith. God did not promise Abraham a child through Hagar but through Sarah. God did not promise that following the law would make you righteous. The law can only show you that you are imperfect because only God can change your heart.
Sarah, who represents faith, is the mother of us all. All believers have one major thing in common and that is faith in God. Faith is the mother of us all. Now we, like Isaac, are sons and daughters of the promise. Those who believe in the works of the law persecuted those who believe in the Lord Jesus Christ and are born after the Spirit. It was the same in the past just as it is now.
What does the scripture say? "Cast out the bondwoman and her son: for the son of the bondwoman shall not be heir with the son of the freewoman." Galatians 4:30 Cast out the Old Covenant and them that choose to be justified by the works of the law because those of the works of the law will not be heir with Christians, who by faith in Jesus Christ, are born of the Spirit and partakers of the New Covenant and the promises.
For you are all children of God by faith, no matter your race, and heirs according to the promise. God by his Spirit has written his laws in your mind and in your heart. You have received circumcision of the heart as the sign of the New Covenant. Therefore, brothers and sisters you are not children of the bondwoman but of the free.
Study Scriptures: Genesis 3:15, Genesis 15, Exodus 2:24, Exodus 24:3, 6, Galatians 3 and 4, Romans 4, Jeremiah 31:31-34, Hebrews 10:16-18, Isaiah 42:5-9, Matthew 26:26, Hebrews 7-10, 2 Timothy 1:13-14