A short excerpt from a paper I recently wrote on an article by Robert Jenson. Here is one way to think about how prayer works. Prayer is a means in the plan of redemption and it moves along the plan of redemption.
Christians, through prayer, really are involved in providence.
When we understand this within the immutability of God’s decree, we see that God brings all things to be through his good pleasure. As beings in time, we can be confident in the certainty of God’s immutability; that he will always remain faithful. At the same time, we can, as part of God’s immutable plan, be certain that our prayers are means that truly are significant in God bringing out his plan of redemption. We can trust this is true, because God is not before us temporally, but is before us as the eternal king. He is both the beginning and the end. This means we don’t need to be fatalists. As Christians, we are living, breathing, free means within the immutable plan of redemption.