The predominant religion is Theravada Buddhism. Animism is common particularly among the mountain tribes. Buddhism and spirit worship coexist easily, even though phi worship is officially banned. The clearest example of this is the Baci ceremony which all Buddhist lowland Lao practise regularly at every major life event such as birth, marriage and death. The ceremony calls all the good spirits together to ward off the evil spirits and to get strength for these important moments in life. Most Christians (primarily Roman Catholic) have left since 1975.