Experientially, we know that Christian prayer can accomplish miracles. When we consider the omniscience, and sovereignty of God, we know that our prayers don’t change anything that has already been spoken by God, once and for all. We experience life one way. We think something that seems to contradict what we experience. If we can’t square them, it is because we are limited. Some people can justify the sovereignty of God with the experiences of the creature. We don’t look down on those who can’t. I would hope that those who can’t won’t look down on those of us who can.
Consider that God decrees the ends and the means. As I pray for something according to God’s will, as explained in the progressive revelation of His word, I am sanctified. My thoughts and feelings are focused on God and His will. The situation I am praying about changes. I attribute it to God answering my prayers. He willed it to happen by using me to pray at exactly the time He decreed, in the way He decreed, so He could answer in the way that He decreed. The reality of His decree was actual at the moment He spoke everything into being. We are part of that decree. We exist in space-time, when and where He decreed. As our reality unfolds, we are not able to perceive how eternity is experienced. If we can accept that there is an infinite instance that contains our finite, linear experience, and transcends it, then we can also appreciate how the sovereign decreed will of God, and the experience of man are related. Does prayer change things? Yes it does, in our material experience. It changes, here because it was changed before in eternity.