The religion started when a baptist preacher named William Miller taught that Jesus was coming back in 1844. He had thousands of followers who sold all of their earthly goods in anticipation of this, and when it didn't happen many despaired:
https://en.wikipedia.org/wiki/Great_Disappointment
They moved on from this by saying that it happened in Heaven instead of earth, that Jesus entered into an "investigative judgment" period, and thus the SDA religion was born. The investigative judgment is when Christ looks over the works of believers to see who is worthy of eternal life. This is a direct attack on the substitutionary atonement.
They have a prophetess named "Ellen G White" who wrote countless books
They deny the Trinity
They think Jesus is Michael the Archangel
They teach the Atonement wasn't enough..we will be judged by our works and that will determine our salvation.
They teach that in 1844 Jesus Christ entered into a special "investigative judgment" period to blot out the sins of the righteous, judging case by case according to works
They teach Satan is the scapegoat for our sins and will be punished for all of our sins
Ellen G White:
"When Christ, by virtue of His own blood, removes the sins of His people from the heavenly sanctuary at the close of His ministration, He will place them upon satan, who, in the execution of the judgment, must bear the final penalty.""
Again, this is an attack on the sufficiency of Christs atoning work on the cross
They believe they are the "remnant church". If you get baptized into SDA you have to state you believe they are the remnant church. They believe they are the only true church
They also teach that Sunday worship is either the Mark of the Beast or that Sunday worshipers will take the mark
There are more than these, and because of these beliefs, I would never recommend anyone go to an SDA church. I hope some of them are saved, but I don't really know. If they think Jesus is Michael the Archangel and that they're saved by works they are talking about another Jesus and another gospel.
EGW wrote over and over that we are saved by grace---
The mother is God’s agent to Christianize her family. She is to exemplify Biblical religion, showing how its influence is to control us in its everyday duties and pleasures, teaching her children that by grace alone can they be saved, through faith, which is the gift of God. This constant teaching as to what Christ is to us and to them, His love, His goodness, His mercy, revealed in the great plan of redemption, will make a hallowed, sacred impress on the heart.14
The Review and Herald, September 15, 1891.
Therefore there is no occasion for one to glory over 402another or to grudge against another. No one is privileged above another, nor can anyone claim the reward as a right. {COL 401.0}
Christ’s Object Lessons, p. 402.1
The first and the last are to be sharers in the great, eternal reward, and the first should gladly welcome the last. He who grudges the reward to another forgets that he himself is saved by grace alone. The parable of the laborers rebukes all jealousy and suspicion. Love rejoices in the truth and institutes no envious comparisons. He who possesses love compares only the loveliness of Christ and his own imperfect character.
{COL 402.1}
While we are to be in harmony with God’s law, we are not saved by the works of the law,FW 95.3
We absolutely do not deny the Trinity.
There are biblical reasons for believing that Michael and Christ are the same, so we are not the only denomination to think so.
Read Leviticus 16 about the ritual of the scapegoat, instituted by God Himself.
Lev 16:7 And he shall take the two goats, and present them before the LORD at the door of the tabernacle of the congregation.
Lev 16:8 And Aaron shall cast lots upon the two goats; one lot for the LORD, and the other lot for the scapegoat.
Lev 16:9 And Aaron shall bring the goat upon which the LORD'S lot fell, and offer him for a sin offering.
Lev 16:10 But the goat, on which the lot fell to be the scapegoat, shall be presented alive before the LORD, to make an atonement with him, and to let him go for a scapegoat into the wilderness.
On the day of atonement 2 goats were brought to the High Priest. One represented Christ and was sacrificed and the blood used to cleanse the tabernacle of sins---
Lev 16:20 And when he hath made an end of reconciling the holy place, and the tabernacle of the congregation, and the altar, he shall bring the live goat:
Lev 16:21 And Aaron shall lay both his hands upon the head of the live goat, and confess over him all the iniquities of the children of Israel, and all their transgressions in all their sins, putting them upon the head of the goat, and shall send him away by the hand of a fit man into the wilderness:
The scapegoat represents Satan---There is absolutely no attack on the cross, nor can there be when came from God Himself!
The blood of Jesus forgives our sins-they are placed on Satan and he pays the final penalty for those sins----which seems only fair as he is the root cause of all sin.