First Reading: Genesis 17:1–7, 15–16
When Abram was ninety-nine years old, the LORD appeared to Abram, and said to him, "I am God Almighty; walk before me, and be blameless. 2And I will make my covenant between me and you, and will make you exceedingly numerous." 3Then Abram fell on his face; and God said to him, 4"As for me, this is my covenant with you: You shall be the ancestor of a multitude of nations. 5No longer shall your name be Abram, but your name shall be Abraham; for I have made you the ancestor of a multitude of nations. 6I will make you exceedingly fruitful; and I will make nations of you, and kings shall come from you. 7I will establish my covenant between me and you, and your offspring after you throughout their generations, for an everlasting covenant, to be God to you and to your offspring after you. 15God said to Abraham, "As for Sarai your wife, you shall not call her Sarai, but Sarah shall be her name. 16I will bless her, and moreover I will give you a son by her. I will bless her, and she shall give rise to nations; kings of peoples shall come from her."
Second Reading: Romans 4:13–25
13For the promise that he would inherit the world did not come to Abraham or to his descendants through the law but through the righteousness of faith. 14If it is the adherents of the law who are to be the heirs, faith is null and the promise is void. 15For the law brings wrath; but where there is no law, neither is there violation.
16For this reason it depends on faith, in order that the promise may rest on grace and be guaranteed to all his descendants, not only to the adherents of the law but also to those who share the faith of Abraham (for he is the father of all of us, 17as it is written, "I have made you the father of many nations") — in the presence of the God in whom he believed, who gives life to the dead and calls into existence the things that do not exist. 18Hoping against hope, he believed that he would become "the father of many nations," according to what was said, "So numerous shall your descendants be." 19He did not weaken in faith when he considered his own body, which was already as good as dead (for he was about a hundred years old), or when he considered the barrenness of Sarah's womb. 20No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, 21being fully convinced that God was able to do what he had promised. 22Therefore his faith "was reckoned to him as righteousness." 23Now the words, "it was reckoned to him," were written not for his sake alone, 24but for ours also. It will be reckoned to us who believe in him who raised Jesus our Lord from the dead, 25who was handed over to death for our trespasses and was raised for our justification.
Gospel: Mark 8:31–38
31Then he began to teach them that the Son of Man must undergo great suffering, and be rejected by the elders, the chief priests, and the scribes, and be killed, and after three days rise again. 32He said all this quite openly. And Peter took him aside and began to rebuke him. 33But turning and looking at his disciples, he rebuked Peter and said, "Get behind me, Satan! For you are setting your mind not on divine things but on human things."
34He called the crowd with his disciples, and said to them, "If any want to become my followers, let them deny themselves and take up their cross and follow me. 35For those who want to save their life will lose it, and those who lose their life for my sake, and for the sake of the gospel, will save it. 36For what will it profit them to gain the whole world and forfeit their life? 37Indeed, what can they give in return for their life? 38Those who are ashamed of me and of my words in this adulterous and sinful generation, of them the Son of Man will also be ashamed when he comes in the glory of his Father with the holy angels."