Religious rituals, like going to church on Sunday or praying, have two purposes. First, they are to reinforce preexisting beliefs, and make them salient in a person's life. For example, making sure to eat a kosher meal, or praying before a meal, reminds that person on a regular basis of their beliefs. A person is more likely to act on their beliefs if they are cognizant of them.
The second reason is to induce a phenomenological experience. Many church services are structured in a way to try to get the congregation to "feel" the presence of god. Every mystic ritual was created with this purpose. Entheogens were used with this intent. Phenomenological experiences are more important to religion, since they are what creates strong and lasting believers.