Just as in the arts of painting, poetry, music, and dance, in Zen Buddhist liturgy we manifest that which is known to us intuitively in the form of a visible, tangible reality. In this way, liturgy tends to make palpable the common experience of a group. Zen liturgy uses chanting which is grounded, driven by a steady rhythm, like a heart beat, very much in the here-and-now. Zen altars strive for a similar effect of simplicity and directness.
In theistic religions, liturgy reaffirms our relationship with God. Zen Buddhism, by contrast, is nontheistic, so its emphasis is on realizing our Buddha nature, the nature of the self. Therefore, all of Zen's rituals point to the intimacy between the self and the ten thousand things. Zen liturgy is upaya, skillful means. Like zazen and all the other areas of training, it functions as a way of uncovering the truth which is the life of each one of us. Zen study, face-to-face teaching, work practice, academic study, art practice, body practice, the Precepts all point to the same place: the nature of the self. Skillful means are necessary because each one of us, just as we are, is already perfect and complete, but this has to be realized as the functioning of our lives. And for practice to function, for liturgy to function, it must be wholeheartedly engaged.
Listen to the Maha Prajna Paramita Heart Sutra