Rock has been criticized by some Christian religious leaders, who have condemned it as immoral, anti-Christian and even demonic. However, Christian rock began to develop in the late 1960s, particularly out of the Jesus movement beginning in Southern California, and emerged as a sub-genre in the 1970s with artists like Larry Norman, usually seen as the first major "star" of Christian rock. The genre has been particularly popular in the United States. Many Christian rock performers have ties to the contemporary Christian music scene, while other bands and artists are closely linked to independent music. Since the 1980s Christian rock performers have gained mainstream success, including figures such as the American gospel-to-pop crossover artist Amy Grant and the British singer Cliff Richard. While these artists were largely acceptable in Christian communities the adoption of heavy rock and glam metal styles by bands like Petra and Stryper, who achieved considerable mainstream success in the 1980s, was more controversial. From the 1990s there were increasing numbers of acts who attempted to avoid the Christian band label, preferring to be seen as groups who were also Christians, including P.O.D and Collective Soul.