Adventists, even if they are your friends, can get upset when you challenge their Sabbath. I call it ‘their Sabbath’ because I do not deem it God’s Sabbath, just as Jesus when debating with the Pharisees and scribes used the words ‘your law’ to nominate the law that had originated with God but which was being used by this class to resist and deny the life that had appeared among them in the person of Jesus Christ.
Adhering to something that God has passed by is just as much idolatry as worshiping something that is not in fact His person. In the new testament age we are gifted with His Person among us and in by His Spirit. To remain in union with the abstraction of the law and relating to Jesus through it or a piece if the law like the Sabbath is idolatry. But to make a hybrid denomination out of law, the Sabbath and Jesus is both a presumption and a preposterous example of a false christ. Why? A christ subordinate to the law is not the Christ of God.
Adventism is pretty much Sabbath-keeping. It is the navel of Adventism. A challenge to Adventism by a former Adventist comes as a kick in the shins to those embedded in its sense of sacredness. This is because The Sabbath is Adventism’s holy icon and representative symbol of itself and what it means to gain favour with God.
Yet many voices have been raised in protest against the legitimacy of the Sabbath and against Adventism as a system – for it is more an ideology than a faith. It cannot escape this since it is an emanation of the law. It is intrinsically legalistic for the same reason that Islam is a legalistic religion: It tends towards an ideology and a cultic one at that. The subversive nature of the Sabbath is not only that Jesus is our Sabbath and our ‘rest for human restlessness.’ Its subversion of the Kingdom Jesus began is found in the semi-idolatrous practice of making the Sabbath one’s grace and one’s Messiah. This is a master stroke of the Enemy that vitiates the influence of Jesus and fosters spiritual insecurity. As a young man astutely observed, the ‘false grace’ suffocates one’s union with Jesus.
The so called Sabbath-Truth would have to one of the most clever substitutions of an idol for the life of Jesus ever perpetrated on the Christian church. Adventism rails against last days deceptions with never a thought that it is itself an exquisite example of deception.
It's significant that so many pioneers came to Adventism via Bible studies. But following Miller these studies have always been a chain of disconnected scriptures with no common meaning, welded into a supposition and a fantasy under the pseudo-prophetic guidance of Mrs White. Christ did not come, but not to worry. These folk theologians constructed another story out of the bizarre notion of the Investigative Judgment. There are intelligent people who have not abandoned these fantasies or if they have off-loaded the more specious of them have been able to rationalise the work of Desmond Ford and Walter Rea in a way that enables them to excuse Ellen’s heresies and literary dishonesty. Their identity in this community seems more important to them than the truth, discovering the truth and setting themselves and other captives free into the glorious liberty of the real gospel and in so doing annulling this ‘other gospel’ which many of their fathers ministered as the curse that Paul said it would be.
Neither Miller or the pioneers or the theologians that taught me during the 1960s had any understanding of the new covenant. The Bible was a seamless whole to them with the new testament just being a the post cross part of the book that was essentially the same as the first part but with Jesus help to keep the law. But that’s not it at all. Jesus is here to be our life.
One would hope that anyone could see that this was an attempting mending of an old wineskin. Jesus had come to save us not only from rebellion but from religion. Anthony Buzzard writes, “
Reflection over many years of teaching and study has brought us to the settled conviction that one of the most fatal misunderstandings of Jesus and the New Covenant occurs when we try to mix two different systems, the Old and the New. God is no longer dealing with mankind in the terms He authorized through Moses. If, with full sincerity and a desire to obey God, we approach Him on a basis which He does not prescribe for us under the New Covenant brought by Jesus, we are liable to inflict upon ourselves a terrible theological wound. Ignorance of the New Covenant is as divisive as it is destructive of spirituality.
We either have one master of we don’t. We either have Jesus’ gospel or another gospel that binds people in the name of God and spreads like a cancer in the body of Christ as though it is legitimate and has a right to be there.

Buzzard, Anthony. The Law, the Sabbath and New Covenant Christianity (Kindle Locations 74-78). Restoration Fellowship. Kindle Edition.