God announced that Eve could not take the ax in her hands, but her son would. What hope this would have given those first parents. Their son would win the victory for them over the Enemy. Adam's faith and hope in this promise of God comes out as he names his wife Eve, the mother of all living (Gen. 3:20). All humans would come forth from Eve. The one son would be her son. Eve's faith similarly bubbled up in excitement at her firstborn: "I have gotten a man with the help of the Lord" (Gen. 4:1). Eve thought Cain was the son to crack the skull of the Serpent. The son has come’God kept his promise.
We know, of course, how Cain ended up shattering Eve's hopes. Yet, Adam and Eve's faith was not snuffed out. When Seth was born, Eve again let words of faith roll off her tongue: "God has appointed for me another offspring instead of Abel, for Cain killed him" (Gen. 4:25). Adam and Eve realized that not all their kids would call on the name of the Lord; only one of their sons would be that victorious offspring. In faith, Eve named Seth as the appointed one, the replacement. Through him, God's promise would find its fulfillment.
It is this faith, this hope in God's promise, that is then narrated in the genealogies. As history spreads from east of Eden to cover the globe, God records his fidelity to his promise through genealogies. Every son of the faithful is named in hope of God's promise. Believing parents named their sons praying, "Will this be the son?" Genealogies are not tongue twisters like Dr. Seuss's Fox in Sox, but they are a record, a stone carving of God's faithfulness. The Lord keeps bringing forth sons, one of whom will eventually deliver his people from the Evil One and the curse. Even after generations, Lamech names Noah saying, "Out of the ground that the Lord has cursed this one shall bring us relief from our work and from the painful toil of our hands" (Gen. 5:29). Lamech looks to the Lord to bring deliverance from the curse through his son Noah.
And on one level, God did just this. The Lord preserved his people from the flood curse through Noah. Yet sin's curse of death still roamed the earth like a predator after the flood. So God's faithfulness continued through the flood and beyond. Out of Noah's three sons, God's promise passed through one, Shem. God kept giving sons and his people kept naming in faith, even down to Abram. Then, as God appears to Abram, his promises are again centered on children, particularly a son. The Lord's making Abram a great nation, with a great name and a blessing to all nations, depends on him having a son (Gen. 12:1’13). The narrative of Genesis focuses on the son of promise. When Abram believes that the Lord will give him a son in his old age, it is reckoned to him as righteousness (Gen. 15:6). After Abraham messes up with Hagar, God confirms to him that the son of promise will be through Sarah (Gen. 17:19). When it comes time for Isaac to marry, Abraham expresses his faith by getting him a wife from his extended family back in Nahor. The promise had to come through Abraham's offspring. Isaac and Rebekah trusted in the same promise. Esau's marriage to Canaanite women displeased both his mom and dad (Gen. 27:46; 28:8), so they send Jacob back to Paddan-aram to get a wife. Through all this history, we see that God's people must express their faith in accord with the promises given to them. The Lord promised a son through whom his blessings would come, so the people must believe God by having sons.
This expression of faith is particularly shown when Jacob returns to Palestine with his two wives and twelve sons. God has made clear that faith in his promises means not marrying Canaanite women. Yet Judah expresses none of this faith for he separates from the covenant community to marry a Canaanite (Gen. 38:2). After having three sons, Judah perpetuates his unbelief by taking the Canaanite Tamar as a wife for his firstborn son Er. But then God intervenes. The Lord executes Er for his wickedness. After Tamar is given to Onan, Judah's second son, the Lord also strikes him down for his wickedness. At this point, Judah must give Tamar to his third son. But, thinking Tamar is bad luck, Judah refuses to do so and he seems to lose all interest in having grandkids.
Tamar, however, possesses the faith Judah lacks. She knows that her only hope as a Canaanite is to become part of the covenant family. She must have a son within the line of Abraham. So she boldly takes matters into her own hands. Disguised as a prostitute, Tamar deceives Judah into sleeping with her. When Judah finds out Tamar is pregnant, he plans to burn her. But when she shows him the signet and staff he gave her as a pledge, Judah declares of Tamar, "She is more righteous than I, since I did not give her my son Shelah" (Gen. 38:26). Tamar's faith in God's promises was reckoned to her as righteousness. God then blesses this heroine with twins and gives her a place in the genealogy of Christ (Matt. 1:3). By faith, Tamar peered forth to behold Christ. She knew her salvation lay in God's promises through Abraham's offspring. By clinging to Judah, she became an heir of God's promises. She received the privilege to name her sons in faith, believing that through one of them Christ would come to deliver her from the Evil One and from the curse of sin.