The Psalmist perceived the Hand of God as steadfastly keeping him safe from the evil and harm. What you think about you bring about. For in spite of all the chaos of that time, the pervasiveness of God's love and compassion was felt, much different than in the lesson from Isaiah. At the time Paul wrote to Corinth, they took what some had witnessed and what others had come to understand through the oral tradition, and viewed it through a human filter of seeing and understanding, to a point of heresy. The writers of the Gospels did this, to assure the message of Good News would be understood and absorbed by the audiences they were working with.
Stories overlap and stories contradict each other.
Sometimes one might even be led to believe there is more than one event, because of the way the facts are revealed. Today's gospel, for example, tells us of Peter's calling and tells us of the calling of the four. Both stories are present in this reading. So it happened in the early church. It happened throughout the history of the Church, and it happens even now, as the history of the Church continues.