Since 1901

Meet religious group that wears special underwear to fight off temptations of the flesh

England: Despite having 15 million Mormons in 185 countries around the world, much mystery surrounds the Mormon religion.

Channel 4 gained exclusive access to the UK movement in Meet The Mormons, as it follows 20-year-old Josh Field, as he becomes a missionary.

His new role as an 'Ambassador of God' requires him to leave home for two years, in which time he's not allowed to see friends or family. Phone calls are limited to twice a year and letters once a week.

Here are seven extraordinary Mormon beliefs the excellent doc also uncovers.

1. Mormons must remain 'sexually clean'

Until they marry, Mormons are prohibited from sexual acts (which includes no self-pleasure).

They have 'temple garments', which they wear underclothes, which acts as a reminder of their covenants eg: no sex, which strengthens their self control.

2. Jesus Christ moved to America following his resurrection

In addition to believing He appeared to his own disciples before ascending to Heaven, Mormons subscribe to the theory that, following his crucifixion, Jesus in fact moved to America and appointed 12 disciples there.

3. Tea and coffee is a sin

Members of the Mormon church can not drink alcohol or smoke.

Moreover, they are not allowed to drink tea or coffee as they believe that God commanded it this.

4. Baptism after death

They believe they have the power to baptise people once they have dies, so even if you weren't a Mormon in life, you can be saved.

5. Jesus Christ asked for their church to be created

The Son of God appeared to founder Joseph Smith almost 200 years ago and said the other Christian churches were not his and had gone astray, queue the birth of the Mormon church.

6. Swimming is prohibited

Young Mormon missionaries are not allowed to go swimming.

7. Marriage can be 'sealed' for an eternity

Couples attend 'sealing' ceremonies in their temple which assure they will be together, even after death.