Is Reiki a religion or a practise?
Reiki can be very spiritual, but it is not a religion. It can be (and is) practised by people of all faiths, from Mormons to Muslims, and it often enhances that faith and leads to spiritual growth. Pope John Paul II also practises Reiki. There are many different types of Reiki, and some of them are probably more suited to people of a certain path. Some traditions are more pagan or New Agey than others, but you can take from or reject aspects of those traditions as you wish.