A name is very important. God changed Abram’s name and He also changed Sarai’s name. Their names needed to reflect who God made them.
Yesterday and today, God revealed His covenant that He made with Abraham. It involved the law of circumcision. This law was for the male Jews. It is not for the females. The Muslims mutilate their women due to their false religion. Circumcision according to God’s law is not mutilation.
God created man and He decreed that circumcision should be done on the 8th day of the male child’s life. At that time in the child’s life, it is not a difficult procedure. This part of the covenant was instituted when Abraham was 99 years old and he also needed to be circumcised. It would have been quite a memorable event for him and for Ishmael, who was also more than 8 days old at this time. God commanded that all the male children under Abraham’s watch were to be circumcised. This applied to those born in his household and to those who were bought with money. All of Abraham’s male descendants also needed to be circumcised.
In verse 14 we see that any Jew that did not want to follow this law, was to be cut off from his people. He had broken his part of this important covenant. This was part of the covenant we looked at yesterday. It was not something that was put out on display. It was a private matter that was between God and the males of Israel.

Genesis 17:15 And God said unto Abraham, As for Sarai thy wife, thou shalt not call her name Sarai, but Sarah shall her name be.
16 And I will bless her, and give thee a son also of her: yea, I will bless her, and she shall be a mother of nations; kings of people shall be of her.
17 Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is an hundred years old? and shall Sarah, that is ninety years old, bear?
18 And Abraham said unto God, O that Ishmael might live before thee!
19 And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.
Gen 17:20 And as for Ishmael, I have heard thee: Behold, I have blessed him, and will make him fruitful, and will multiply him exceedingly; twelve princes shall he beget, and I will make him a great nation.

In verse 15 God continued to show His authority in Abraham’s life. He changed Sarai, Abraham’s wife’s name to Sarah. The name Sarai means “princess. The name Sarah means “noblewoman”. God stated that Sarah would be a mother of nations and that kings of people would come from her. We know that Sarah only had one child and that was Isaac. However, Isaac had two sons and from there many more sons were born.
In verse 17 Abraham expressed his surprise and his excitement at what God had just told him. At his age he was going to become the father of the promised child that God had declared some years back. Abraham wondered how this could possibly happen at his age and the age of his wife Sarah.
God is never late, and again we see that Abraham needed to learn to trust God. Nothing is impossible with God. Every promise that He makes, He keeps. God makes many promises for those who are saved. God’s children need to trust Him in all things. God’s children have been changed by Him at the moment of salvation and they are expected to be different.
As we see in our text, God even changed the name of Abraham and Sarah to reflect who they were. The Bible declares that the saints will have a new name in heaven. The name Christian was given as an identifier to set apart those who believed in the Lord Jesus Christ for salvation. It was a name given to them by the ungodly. It was to identify them as the enemy. Over time, it took on a more friendly meaning. Today it is often times a meaningless name. In the Middle East the word “Christian” often refers to Catholics in one form or another. Even in North America, the word Christian has taken on a much different meaning.
Those who are saved are different. The difference will be identifiable to others. Their actions will reflect the change that God has made in their heart. The Bible helps us to note some of those changes that will be common to all born again Christians. The world has dismissed those changes and has muddied the waters on what a true Christian is. However, we still have the Bible and we can still know the truth today.
God could bless Abraham and Sarah with His promised son because they were His children. God shows us some of the sins in their lives as well as the blessings. We can learn from this if we are saved. We cannot learn to make excuses for sin; rather we can learn the importance of walking by faith. That has always been God’s way of blessing.

I Corinthians 6:19 What? know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?
20 For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God’s.