For a lot of people, I think religion provides this basis or promise of harmony with the world, in a simplified way that stipulates what you should or shouldn't do and how things work, and those people find comfort in having these clear "rules"; we want to be able to rely on our understanding of the world, so that we can act within it with confidence, or faith. Ultimately, the "god" that is present in many religions is synonymous with this absolute truth of how the universe works, it's an unattainable standard that we all try to aim for, intuitively and knowledge-wise, or seek wisdom from, and I believe the intention of prayer is to have a way to get closer to it, to tune the self to the god in order to sense and know this absolute truth more clearly. I reckon that conceptually, prayer and meditation are very similar in this sense, but with a focus on different areas of the self.