One of the things that really strikes me about the Catholic and Orthodox Churches is their insistence on the unity of the human person. As a unity of body and soul, our faith cannot be just about the soul. It must be corporal as well. This makes sense in light of how Christ saved us. God didn't just declare, "you are redeemed." Instead, Christ took on a real substanial human nature, along with all of its physical qualities, offered his human life for our sins, and was resurrected to conquer death for us. The faith is incarnational, and that means including rituals in our praxis.
These rituals have the effect of even bringing our emotions under the command of our reason and our will. We will to serve and love God, but we do not always feel that. These rituals help to direct our emotions, which are part of the human person, to the reasonable goal of willing to serve God above all. They help to subject every aspect of ourselves to God.