I would prefer to call God's people a remnant people, rather than, a remnant church. When you attach the word, church, to it it becomes a denomination and God is not saving a denomination, he's saving a people. Here is how God defines His remnant people.
Revelation 14:12 Here is a call for the endurance of the saints, those who keep the commandments of God and their faith in Jesus.
This definition is found in many denominations other than the SDA. The remnant people of God won't be practicing such things as Christmas, Easter, Good Friday, 40 days of Lent, Halloween, Sunday resurrection, Sunday as the Lord's day. If you do practice these things it doesn't mean you are not part of God's remnant people, it just means you need more maturity in the ways of God. The closer you grow to God and mature in His ways the less fellowship you will be able to find, even among believers.
This is still the heart of God for His people. God does not change.
Deuteronomy 12:29-31 When the LORD goes ahead of you and destroys the nations and you live in their land, do not fall into the trap of following their customs and worshiping their gods. Do not inquire about their gods, saying, ‘How do these nations worship their gods? I want to follow their example.’ You must not worship the LORD the way the other nations worship their gods, for they perform for their gods everything the LORD hates.
When you practice such things as Christmas, Easter, Good Friday, 40 days of Lent, Halloween, Sunday resurrection, Sunday as the Lord's day and so many other things you have adapted to ways of the other nations and are worshiping God the way they worship their gods.