Ben Carson Republican Seventh Day Adventist
Republican presidential candidate Ben Carson speaks with members of the media after the Republican Presidential Debate at the Milwaukee Theatre on November 10, 2015Getty

Dr Ben Carson, a neurosurgeon from Detroit who rose from poverty to become a respected medical practitioner, is edging closer towards the White House. After lacklustre performances in the debates among Republican presidential candidates, he has seen a recent surge in popularity --despite some wacky comments about the pyramids in Egypt.

Footage from 1998 emerged of Carson, 64, espousing his theory that the biblical figure Joseph built the pyramids in order to store grain so people could be fed during a drought. Egyptologists have dismissed Carson's pyramids theory as nonsense. But Carson stood by his "personal theory". And his poll ratings -- which show him on top among Republicans, above Donald Trump and Jeb Bush -- suggest people don't care all that much anyway.

"Now all the archaeologists think that they were made for the Pharaohs' graves," Carson said in the video from the late 1990s, where he was addressing students at Andrews University, a Christian college linked to the Seventh Day Adventists. "But, you know, it would have to be something awfully big if you stop and think about it. And I don't think it'd just disappear over the course of time to store that much grain.

"And when you look at the way that the pyramids are made, with many chambers that are hermetically sealed, they'd have to be that way for a reasons. And various scientists have said, 'Well, you know there were alien beings that came down and they have special knowledge and that's how, you know, it doesn't require an alien being when God is with you'."

The reason Carson was speaking to a bunch of Seventh Day Adventists is because he is one. So what is Seventh Day Adventism? And what exactly do Seventh Day Adventists believe?

US election 2016: Ben Carson pulls ahead of Donald Trump in national pollIBTimes UK

Seventh Day Adventism, a denomination of protestant Christianity, was created in 1863 and derives its name from the followers' belief that worship and rest -- i.e. the Sabbath -- should take place on a Saturday, which is the seventh day, rather than Sunday. This is an Old Testament interpretation, similar to Judaism. Much of Seventh Day Adventism stems from the Old Testament, meaning it is a particularly conservative religion.

The roots of Adventism lay with an American army officer called William Miller, who repeatedly (and unsuccessfully) predicted the return of Christ. This belief in the coming return of Christ remains prevalent in Adventism. One of the founders, Ellen Gould White, is considered by Seventh Dayers to have had prophetic powers. Though she died in 1915, aged 87, her writings are still studied as a source of divine truth.

Among the core beliefs of Seventh Day Adventism -- there are 28 fundamentals, according to the UK church's website -- are the rejection of "unclean meats" (such as pork), alcohol, and narcotics to lead a healthy lifestyle; that all humanity is now involved in a "great controversy" between Christ and Satan; that God demands stewardship of the Earth and nature, which is his gift to humans; and when the rapture comes, God will give the righteous a new, sin-free earth as an eternal home. When the righteous die, according to Adventists, they are unconsciously awaiting the return of Christ, at which point they will be resurrected and transported to God's new earth.

There are nearly 18.5 million Seventh Day Adventists in the world, according to the church, worshipping at nearly 79,000 churches in 216 countries. They also have 7,579 schools across the world. The church claims its "tithes" -- a religious tax paid to governments -- totals more than $2.3bn (£1.5bn) a year.