I am a former Catholic, now a spiritualist. This question is timely for me, as I am developing a presentation on the importance of ritual, both for traditional religions and the recently popular spiritualist or metaphysical beliefs.
The three steps for ritual are preparation, function, closing. The preparation (for an individual) can be as simple as finding a quiet place and centering. The function would be attempting to fulfill the reason for the ritual (some might call it ceremony). The closing is to make a distinct boundary between the ritual and going back to “everyday” life.
A ritual is not necessarily religious in nature; it can be strictly secular. Some of the more well-known secular rituals are installation of public officials. Depending on the office, it can be short and to the point (e.g., the administering of the oath of office), or it can be filled with pomp and circumstances (a Presidential Inauguration, along with all the balls, celebrations, etc).
However, my assumption is that the OP is asking for a spiritual or religious point of view.
One of the main reasons for ritual is to set a mood. In the religio-spiritual sense, this is to set the stage for the group or individual to communicate with the Divine, in whatever tradition. This mood may be set in several ways; in the traditional Catholic ritual (the Mass) the mood is set by prayer and scripture. In some Neo-Pagan rituals, the mood is set by “setting sacred space”, calling upon deities, spirits, angels, etc., for protection. The actual ritual then follows.
The closing, in the Catholic Mass, is generally the blessing and dismissal. The Neo-Pagan closing consists of “closing sacred space”, by thanking all deities, spirits, etc., who have provided protection.
As I was composing this post, I saw your additional question: Does ritual have to include more than one person? Can it be solitary?
The answer is that ritual can be solitary or group. Many “Neo-Shamanistic” (or “Core Shamanistic”) rituals are done by the “shaman” to stay in touch with the other world. Many times a shaman will perform a ritual for a subject who is not in the immediate presence of the shaman.
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