Seventh Day Adventists promote Sabbath-keeping as a primary doctrine. But this goes against the teaching of Scripture on the matter (see Romans 14:5).
"Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day— things which are a mere shadow of what is to come; but the substance belongs to Christ." (Colossians 2:16-17)
Please see this link regarding the Seventh Day Adventist church and the other doctrines they believe in:
https://www.gotquestions.org/Seventh-Day-Adventism.html
True believers of God worship in spirit and truth (John 4:23). Which day we worship should not be our focus. In fact, we should worship God everyday.
Please see more details regarding sabbath keeping:
https://www.gotquestions.org/Sabbath-keeping.html