Seventh Day Adventists
 

Some of them are REALLY dogmatic...like some Oneness

You HAVE to worship on Saturday to some. If you worship on Sunday you have the mark of the beast.

They are not all like that though, but they do believe in keeping the sabbath and dietary laws

The mark of the beast?

The majority believe Sunday worship is the mark of the beast and Sabbath keeping is the seal of God.

The church was started by a false prophet in the 1800's. He told folks that Jesus was to come back to earth in the 1940's.

They all met from around the country on his farm.

It did not happen so he amended his dates.

Then they changed the church name as well.

The Seventh-day Adventist church is the largest of several "Adventist" groups which arose from the Millerite movement of the 1840s. The Millerite movement was part of the wave of revivalism in the United States known as the Second Great Awakening, and originated with William Miller, a Baptist preacher from Low Hampton, New York. Miller predicted on the basis of Daniel 8:14 and the "day-year principle" that Jesus Christ would return to earth on October 22, 1844. When this failed to occur, most of his followers disbanded and returned to their original churches.

Following this "Great Disappointment" (as it came to be known) a small number of Millerites came to believe that Miller's calculations were correct, but that his interpretation of Daniel 8:14 was flawed. Beginning with a vision experienced by Hiram Edson on October 23, these Adventists arrived at the conviction that Daniel 8:14 foretold Christ's entrance into the "Most Holy Place" of the heavenly sanctuary rather than his second coming. Over the next decade this understanding developed into the doctrine of the investigative judgment: an eschatological process commencing in 1844 in which Christians will be judged to verify their eligibility for salvation. The Adventists continued to believe that Christ's second coming would be imminent, although they refrained from setting further dates for the event.

Thats some interesting stuff.I read on Ellen Whites website that they call this Millerite thing the Great Embarassement.

The SDA movement teaches that Christ had a sin nature ,they reason that He could not have been Human without having a sin nature.
They also teach a form of the annihilation of the wicked.
They are Historicist and Premillenial in their eschatology if my understanding is correct.
They consider all who have church on sunday to be daughter of The Catholic church ,but the SDA is Trinity.