Reiki is very spiritual in nature, but there is nothing you are required to believe in before you can learn and use Reiki. Reiki is not a religion. It is a healing art that anyone of any background, religion, or belief system can choose to learn and share if they feel drawn to it. The practice of Reiki does ask you to embrace the Reiki principles which are designed to bring peace and harmony to your life and the world around you.
There have been many accounts about where Reiki came from, but there has been little confirmation of most of these stories. Some say that Reiki originated from Buddhism or that it is a sacred path containing Buddhist concepts or techniques. When I first learned Reiki 12 years ago, my teacher taught us that Dr. Usui had traveled to Tibet to study Buddhist manuscripts where he found the way of sharing positive life force energy which he then adapted into the system he named Reiki. However, in 2006 I worked with a Japanese Reiki master who is also a Buddhist and has done a lot of historical research concerning Reiki in Japan. She claimed there is no connection between Reiki and Buddhism. There are many stories and western accounts about the origins of Reiki, and somewhere in between lies the truth. Regardless, while Dr. Usui practiced Buddhism, he had also studied Christianity and had lived with a Christian family for a time. It is clear he had a very broad background in many religious teachings and philosophies. The clearest and most authentic understanding we have been able to discover is that Dr. Usui originated the system of healing he taught, practiced and named Reiki based on his mystical experience on Mt. Kurama, which is known as the healing Reiki site. He formulated the healing system by making use of his studies in many different areas of knowledge. One of the many stories says Dr. Usui discovered the Reiki symbols in a Tibetan sutra, but even though people have looked carefully, no one has been able to find a Tibetan sutra with Reiki symbols in it. The religious non-affiliation of Reiki is confirmed by Dr. Usui’s own writing, "Our Reiki Ryoho is something absolutely original and cannot be compared with any other (spiritual) path in the world" (Taken from his Reiki Ryoho Original Handbook).
Today, Reiki is practiced by people of all faiths. Catholics share Reiki, as do Buddhists, Hindus, Mormons, Atheists, People of the Jewish faith, Agnostics, Sufis, Pagans, and countless others. Reiki is a healing art that is unrelated to people’s religious beliefs