The Seventh-Day Adventist Church is hard to define. They claim to be Christian, and many of their beliefs are historically orthodox. They believe the Bible to be infallible, they teach the biblical doctrine of the trinity, and so on. Unfortunately, many Adventists rely as much on the (very fallible) writings of founder Ellen G. White, and they often tend toward legalism… the idea that salvation is dependent in part on good works. Many are obsessed with studies about the end times, to the exclusion of other parts of the Bible.
When I was a teen, I went to a church in a Seattle suburb. Another church down the street had a split over doctrine. They were Seventh-Day Adventists.