They wear black badges with white words; they are usually Americans, but they can speak fluent Cantonese; they stand on streets, ready to approach any passer-by; they are the missionaries of Mormonism.
The official name of Mormonism is the Church of Jesus Christ of Latter-day Saints. Founded by Mr. Joseph Smith in 1830 in New York, its headquarters is now in Salt Lake City, Utah.
According to its director of Public Affairs for Hong Kong, Mr. Ho Hok Yuen, there are about 8 million Mormons worldwide, with around 20,000 in Hong Kong.
Mr. Ho said that the church divides Hong Kong into five areas: Hong Kong Island, Eastern Kowloon, Western Kowloon, New Territories and Tolo Harbour. Under each are branches and then districts.
Mormons are not recognised as Christians. In fact, Mormonism is condemned as a heresy by some critics.
The Rev. Lau Yat Chiu of the Lutheran Church explained that heresies are beliefs which pervert The Bible or add new elements to it.
"Mormonism is not Christianity, but a heresy," said he. "Its creeds are different.
"We don't believe in the Book of Mormon or the mission of the resurrected Jesus Christ on the American continent," added The Rev Lau.
According to Mormonism's Press Book, a heavenly messenger showed Joseph Smith gold plates containing the religious and secular history of an ancient American civilization. Joseph Smith then translated it into English which was published as the Book of Mormon in 1823.
Other than The Bible, the Mormons use the Book of Mormon, together with Doctrine and Covenants and Pearl of Great Price.
Nevertheless, Mormons insist that they are Christians.
"We are Christians," said Mr. Ho. "Faith in the Lord, Jesus Christ, is the first principle of our gospels. We use The Bible and we pray in the name of our Holy Father."
Mr. Ho said that the Book of Mormon did not conflict with The Bible.
"We believe that Jesus Christ is the Creator of world and He is still alive. We Mormons are able to perceive the renewed revelation from Him."
Mr. Ho added that Mormons are satisfied that theirs is the "correct interpretation" of The Bible.
However, The Rev. Po Kam Cheong of the Church of Christ in China disagreed.
"The Book of Mormon, instead of The Bible, is their highest authority. Also, they consider Jesus Christ as only a prophet having equal status with Joseph Smith. We thus have different beliefs from them."
Though labelled as a heresy, Mormonism still expects acceptance from other Christian groups.
Said Mr. Ho: "Their accusation is a form of oppression, but we won't take an active role in defending ourselves.
"We hope that friendly meetings with other churches can be held to discuss religious issues, so as to reduce their resistance to us."
He hoped to break the ice through serving the needy together.
"We have participated in community activities, like donating toward the construction of schools in mainland China.
"By serving the common goal of helping others, we hope to give outsiders a deeper understanding of Mormonism," Mr. Ho said.
However, both The Rev. Lau and The Rev. Po said that as long as the Mormons hold different creeds and teachings, Mormonism is a heresy - serving the community does nothing to change its religious status.
The Rev. Po disagreed with the accusation that they were oppressing Mormonism.
"For instance, if we discover that a teacher in our church is a Mormon, we won't dismiss him just because of this," he said.
Meanwhile, the Mormons do not hold back in increasing the sizes of their disciples.
Missionary training programs are provided for disciples who preach. They concentrate on spiritual, linguistic and preaching techniques.
"About two-thirds of our missionaries in Hong Kong are foreigners, mostly Americans," said The Rev Po.
There are minimum preaching periods for both male and female missionaries, which are two years and 18 months, respectively. During these periods, the missionaries are responsible for their own living expenses, including the rent of the hostels provided by the church
Explained Mr. Ho: "Foreign missionaries are mostly students at our church's universities. Preaching postpones their studies. Yet, they would be highly appreciated when they return home, and credits can be claimed for preaching overseas.
"Missionaries have to follow many rules. For instance, they are prohibited from drinking coffee and tea. Time to return to hostels and locations to preach are also limited. Besides, they have to work in pairs to check each other against wrongdoing, like impoliteness and loss of temper."
Despite these regulations and the postponement of studies and careers, many disciples still devote themselves to preaching.
Mr. Au Fok Yan, 20, is one of the missionaries. He said, " I will never regret being a missionary. This is because I can help outsiders to understand our religion."
Another missionary, Miss Pedra Christensen, 23, an American, said, "Preaching gives me self-confidence and strengthens my faith in Holy Father. It's worthwhile even though I had to leave my motherland and come to a strange place."
On one hand, Mormonism is supported by its own disciples. On the other hand, it is being criticised by other Christians.
Ms Ho Fung Yee, 38, is a Christian. She condemned Mormons as "deceiving spirits misleading people"
Added she: "We Christians will never have any contact with them, as our beliefs diverge.
"We can do nothing besides strengthening our religious foundation. It may seem negative. Yet, Hong Kong has freedom of religion, and everyone can believe whatever they want. God is tolerating them.
"Besides, according to Jesus Christ's Revelation, anyone adding anything into the prophetic words of The Bible will be accused and punished by God."
The Rev. Lau evaluated the significance of heresies like this:
"From the social point of view, heresies have no actual harm at all. However, from the religious perspective, they adversely affect how people can be saved by God."