Waiting is one of the most difficult things we ever have to do. Waiting is hard. We always want everything "now". But waiting is often what God asks us to do. Remember "they who wait for the LORD shall renew their strength ..." The LORD is our strength, so waiting for Him is how we become strong. Still waiting is hard.
Abram knew a lot about waiting. In Genesis 12:4 we read that "Abram was 75 years old when he set out from Haran." At that time God promised to make him into a great nation, bless him, make his name great, make him a blessing, bless those who bless him and curse those who curse him, and bless all nations through him. (see Genesis 12:2-3) However, after 11 years, Abram still had no child. I imagine waiting was hard for Abram.
In Genesis 16, we read about Abram and Sarai's plot to help God along. Sarai gives her mistress Hagar to Abram and tells him, "The LORD has kept me from having children. Go, sleep with my maidservant; perhaps I can build a family through her." (Genesis 16:2 - NIV) So Abram does as his wife asks him to do and Hagar bears a son named Ishmael. But Ishmael is not the one through whom God will fulfill His promise to Abram. After a brief time away, Ishmael returns to his father's household where Abram raises him as his own son. 13 years pass between then and what we will read today.
So when we read today's scripture we can imagine Abram's reluctance toward wholehearted joy at God's promise.
(Read Genesis 17:1-27)
Abram is now 99 years old. I imagine he and his wife Sarai have largely given up on having a child of their own. Yet God comes to him again with a promise. God promises him - descendants and land, as he has done before, but God also promises him HIMSELF. God establishes His covenant with Abram (now Abraham) in verse 7, "I will establish my covenant as an everlasting covenant between me and you and your descendants after you for the generations to come to be your God and the God of your descendants after you." God promises Himself to Abraham and Abraham's descendants.
This is God's promise, but what does God expect from Abraham? Verse 10 says, "This is my covenant with you and your descendants after you, the covenant you are to keep: Every male among you shall be circumcised." The only thing God asks Abraham to do is to become circumcised and then to circumcise every male in his household. Circumcision becomes a sign of Abraham's faith in God.
Still Abraham remains reluctant, especially when God says Sarai (now Sarah) will have a child. Here Abraham's reluctance becomes shocking disbelief. "Abraham fell facedown; he laughed and said to himself, 'Will a son be born to a man a hundred years old? Will Sarah bear a child at the age of ninety?" It seems too good to be true. Abraham laughs to keep from crying. Is God now going to fulfill His promise against all odds? Why now? Why not 20 years ago? It all seems too incredible. Yet this is God's plan.
"Then God said, 'Yes but your wife Sarah will bear you a son, and you will call him Isaac.'" As the footnote says Isaac means "he laughs". So God confirms His promise and wants the whole world to know just how incredibly unbelievable this is by naming the child Isaac to show the world that even Abraham and Sarah laughed at the thought of it. Nothing is impossible for God! When God makes a promise He always keeps it. God is faithful.
So now I think there are two ways we can "go deeper" together here.
First, if you want to tell a story about a time when you "waited for the LORD" and He renewed your strength, we would love to hear it.
Second, if you want to talk about God's covenant to Abraham sealed by circumcision in relationship to God's new covenant (which in my humble opinion is really not that "new") fulfilled in Jesus sealed by baptism, there is certainly room for that here as well. In this regard I would direct us to two scriptures in the New Testament to get our conversation started. Read Galatians 3:1-29, ff but especially verses 3:26-29, also read Colossians 2:9-12. How does God's promise to Abraham relate to salvation by faith in Jesus Christ? Also how do the "signs and seals" of those promises relate (i.e. circumcision and baptism)?