The non-believer may suggest this similarity comes from people deluding themselves into all believing the same illusion. The stories are all the same, such a person suggests, because people expect the same thing to happen and they change their recollections to match what they believe happened. Of course, that can happen. Over many years of working at church youth camps, I have heard people give testimony that's clearly dressed up or molded in order to fit a preconceived framework. Some of the people are sincere: They believe this is what a testimony should sound like, so they will revise some details and lose some others so it fits. Others may want attention. And others may have no clear reason: I love them, but sometimes teenagers are nuts.
But the repetition can serve a purpose. It can remind a person in the midst of trouble that they can call upon the Lord for help in time of trouble. And although he may not respond in the way they want him to, history proves he does respond. In Psalm 77, Asaph demonstrates what this can look like. He opens with a statement of the problem, and then verses 3-10 elaborate on it. True to the non-believer's complaint, the lament in those verses sounds like that in quite a few other psalms, both by Asaph and by David himself.
Then in verse 11, Asaph starts to give reasons why he turns to God for help. God has helped in the past, therefore God will help now. And only the shallowest understanding believes that the God of the universe will do exactly what is asked. He knows that repeating the history of God's assistance is much more a means of self-reassurance than it is a list of reasons why God needs to get off his duff and get to work now.
But in this case, Asaph doesn't just talk about ordinary help God might have provided. He goes for the big one. He recaps Exodus. In verse 13, he asks what God is so great as God -- the God who demonstrated clear superiority over whatever deities the Egyptians worshiped and whose supremacy every practicing Jew recited daily in the shema. In verses 14 and 15, he sums up all of the protection, rescue and empowerment God provided the Hebrews from the day they walked out of Egypt.
This story is the big story. This story is the foundational history of the people of Israel, the one that has kept them together for almost five thousand years. Asaph brings out a sledgehammer -- which might make us wonder what problem he's dealing with. Some scholars suggest the exile to Babylon, since they believe Asaph wrote his Psalms much later than King David.
I think that's entirely possible, but my mind is also drawn to another possibility. Perhaps Asaph recalls this version of the Exodus story for its own sake and not because of the size of the issue he faced. Perhaps he understands that God's presence with the people is the same always, and every story somehow reflects back on the Exodus story. The threat could be existential, like bringing a sheep to a chariot fight when your back's up against the Red Sea. It could be less so. But either way, God's salvation comes to the one who calls on him. Again, it's God's salvation, so it might not look like what we say we want, but it is salvation.
A cynical look at those redemption stories sees intentional or unintentional editing in order to make them sound the same. But the believer sees the similarity as evidence of God at work. Large or small, every salvation echoes the great salvation, brought to us on Calvary. Are many of them similar? Sure.
But so are sunsets and we rarely get tired of them.