The one hundred fifty Psalms are arranged in an order that has reason and meaning. Psalm one is the introduction to all the others, as Basil the Great wrote around 360 AD:
Like the foundation in a house, the keel in a ship and the heart in a body, so is Psalm 1 a brief introduction to the whole structure of the Psalms. For when David intended to propose in the course of his speech to the combatants of true religion many painful tasks involving unmeasured sweats and toils, he showed first the happy end, that in the hope of the blessings reserved for us we might endure without grief the sufferings of this life.
John echoes David in the last verse of his letter in today’s reading: I have written all this to you so that you who believe in the name of the Son of God may be sure that you have eternal life. NJB
The prayer of Jesus as recorded by John in his Gospel is a powerful description of how it all works, how God brought all the pieces together into one great victory over sin. Jesus in faith chose the Twelve to carry on his work. When one faltered, he was replaced. That has become the pattern of the Church. By taking up the work of the first saints, we too can become saints. We too can look forward to the glory Jesus described in John 17:5, just before our reading today: Now, Father, honour me in your own presence with the glory that I knew with you before the world was made. Phillips
Jesus was sent into the world and we are sent into the world. Before the glory, there is the fight. The military gives out medals for bravery to those who were in the fight. We modern Christians in the US have become used to the comforts of pew sitting. We seek pleasant music and preaching to lifts us without the inconvenience of having to help the poor, the disabled, the sick, the dying, the helpless, the homeless, the unpleasant ones.
Look back at chapter 16 of John, verse 2: the time will come when anyone who kills you will think he is serving God! CJB Jesus made it abundantly clear that killing is never the answer, but sadly, Christians are killed by other Christians every day, quite apart from the brutality of ISIS. Being a follower of the Son of God is not easy. If you want easy, you joined the wrong club.
Be righteous and do good.