The reading is from St. Paul's Letter to the Galatians 2:16-20
Brethren, knowing that a man is not justified by works of the law but through faith in Jesus Christ, even we have believed in Christ Jesus, in order to be justified by faith in Christ, and not by works of the law, because by works of the law shall no one be justified. But if, in our endeavor to be justified in Christ, we ourselves were found to be sinners, is Christ then an agent of sin? Certainly not! But if I build up again those things which I tore down, then I prove myself a transgressor. For I through the law died to the law, that I might live to God. I have been crucified with Christ; it is no longer I who live, but Christ who lives in me; and the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me.
The Gospel According to Mark 8:34-38; 9:1
The Lord said: “If anyone wishes to come after me, let him deny himself and take up his cross and follow me. For whoever would save his life will lose it; and whoever loses his life for my sake and the gospel’s will save it. For what does it profit a man, to gain the whole world and forfeit his life? For what can a man give in return for his life? For whoever is ashamed of me and my words in this adulterous and sinful generation, of him will the Son of man also be ashamed, when he comes in the glory of his Father with the holy angels.” And he said to them, “Truly, I say to you, there are some standing here who will not taste death before they see the kingdom of God come with power.”