They claim that the 30,000 people in Britain who enjoy yoga - long considered harmless by the public at large - are unaware of the "dangers".
Not only, according to one group, the Reachout Trust, is yoga in essence a part of Hinduism and may lead to out-of-body experiences, but also it can have occult links, says another, the Agape Christian Fellowship, which says in a leaflet, Yoga - the truth behind it: "Yoga is cleverly disguised devil-worship and has nothing to do with the TRUE GOD and Father of Our Lord Jesus Christ - HE FORBIDS IT!"
A spotlight was shone on the religious tizzy that yoga can get people into when a Japanese yoga teacher in Bideford, Devon, Atsuko Kato, was banned last week from using a Salvation Army hall for her class after complaints by parents of children who used the hall for other activities, claiming that yoga was a cult activity involving ritual and chanting. Ms Kato says she was simply leading "a class about exercise, breathing, relaxation and a bit of meditation".
Yoga's Christian opponents say the problem lies in its links with Hinduism. Yoga forms an important part of the Hindu meditative process and one of the aims of Hinduism is to come together with a higher being, even become God.
"Yoga is a way for the Devil to gain entry into a practitioner's life," says a Christian former yoga enthusiast quoted in the Agape Fellowship's leaflet. Doug Harris, director of Reachout, a less fundamentalist organisation than the fellowship, feels that yoga is not compatible with Christianity and thus should not take place in a church hall.
He spreads his message through literature and talks all over the country and says he has "written explanatory letters to ministers who show concern for the potential conflict".
All this leaves Britain's yoga enthusiasts bemused. They acknowledge that there are many forms of yoga and John Cain, chairman of The British Wheel of Yoga, encourages people to learn with a teacher certified by The British Wheel. They have approximately 1,700 registered instructors who teach in local education authority halls and sports centres throughout the country.
Mr Cain sees yoga "not as a religion, but as a spiritual practice that will strengthen your beliefs".
He views the opposition to yoga "with a sense of sadness about their misunderstanding" and mentions the names of a nun and a practising minister who are happy to talk about the benefits that yoga has given them.
One such minister is the Rev Jonathan Hopcraft from St John's, Wolverhampton, who has practised yoga for many years and does not find any conflict with his faith.
Despite several appearances in the press, he has not received any information from anti-yoga groups, but he is cautious in his support. "I can understand their position, as some groups are secular but some are based on Hinduism, especially the mantra," he says.