A religion with origins in Japan is quickly amassing a following in Uganda, winning converts in a sleek campaign that has attracted the attention of Christian clerics offended by its beliefs.

Happy Science advertises itself as a global religion with a goal of teaching "the truth about life, the world and ourselves." The religion says it's grand mission is to create a world filled with love, peace, harmony and prosperity.

The success of Happy Science in Uganda was put on public display late last month at a lecture given by the religion's middle-aged Japanese founder on his first visit to Africa. Buses decorated with the image of Happy Science founder Ryuho Okawa ferried people from all over Uganda to attend his lecture inside the national stadium, causing traffic jams and upsetting athletes who had planned to use the space for Olympic trials.

Happy Science officials do not know precisely how many converts they have won since coming to Uganda in 2008, but they say most of the 10,000 people who attended Okawa's lecture were believers. Uganda's population, one of the youngest in the world, is heavily Christian, and Happy Science officials want to use the East African country as a springboard for what they hope will be success across Africa.

But the group's visibility, thanks to old-fashioned missionary work and the frequent appearance of members on national television, has brought scrutiny. Some Christian clerics have gone on the offensive, saying the religion should not be allowed to take root in Uganda. They are especially hostile to an essential part of Happy Science: that Okawa, the 55-year-old former market trader who started the religion in 1986, is also the deity.

"It's an abomination for Okawa to come and tell us that we should bow and worship him," said Martin Ssempa, a well-known Pentecostal pastor who is popular with young Ugandans. "This man is arrogant and he is also misguided. People who claim to be God are either impersonators or comedians. I have not found Okawa funny."

Happy Science officials said in an interview with The Associated Press that the religion is open to all who show interest, and that those offended by its beliefs are free to stay away.

"Master Okawa is a part of the El Cantare consciousness," said Brian Rycroft, the South African head of Happy Science in Africa, referring to the deity's name in Happy Science teachings. "You could say he is one with God."

A Happy Science temple in the Ugandan capital is decorated with a golden statue built in the likeness of Okawa. The fine art is the holiest part of all Happy Science temples, members said, advising against photographing the altar. Those wishing to join Happy Science make a simple vow of allegiance to Okawa.

"The condition is only one: faith in El Cantare," said Tomohiko Nakagawa, who heads the Ugandan branch of Happy Science.

While some Pentecostal clerics say Happy Science is far removed from conventional spirituality, some aspects of the religion from Japan can seem to have an affinity with charismatic Christianity. Happy Science teaches that miracles do happen, that demons can be chased away, and that individual success and peace can be achieved in return for deep faith. Officials said Happy Science has about 12 million members spread in more than 90 countries, including the U.S.

Robert Lutwama, a member of Happy Science in Uganda, said most of the converts were "disappointed in life and with other religions."

"I found Happy Science quite an open door for my mind," said Mariam Nantabaazi, a convert from Islam. "There's unity here, which was lacking within the Muslim community."

Uganda has a history of openness toward foreign proselytizers, notably in the 1980s when a succession of Western television evangelists won millions of converts to Pentecostalism. AIDS was a major factor then, with the sick and affected hoping for miracles. This time, some say, rampant poverty is driving the success of religions such as Happy Science.

"Happy Science tells people what they want to hear," said Solomon Male, a Pentecostal cleric who is a fierce critic of Happy Science. "The people who join Okawa hope that he is going to give them money. He's actually targeting people with real-life needs."

Robby Muhumuza, a researcher who has written a book on false teachings and who attended Okawa's lecture in Kampala, said Happy Science has manipulated Ugandans such as the students who believed Okawa's lecture would be a seminar about the kind of science taught at school. Muhumuza said the group's missionary work — including the distribution of mosquito nets and the awarding of scholarships to rural schoolchildren — had proved effective in the push for converts.

"They see (Happy Science) as an investor from Japan," he said of the converts. "Most of them are not serious followers, but they are hoping to get some benefits."

Declining to discuss any criticisms, Happy Science officials said they were not in competition with other religions. Ikuko Kobayashi, a spokeswoman for Happy Science, said the religion strives for "harmony."

Rycroft, the Africa head of Happy Science, said Okawa found Ugandans warm but lacking in self-confidence. Uganda, he said, had the potential to lead the way in Africa.

"Uganda is a kind of source for how this teaching will spread in Africa," Rycroft said. "Uganda has a very important role to play for the whole continent of Africa."