Adventist who apostatize or leave the church seem to follow nearly the same order in their experience. The fact that so many of who fall away, follow the same path needs to be looked at.
First they look at intellectualism or the "wisdom of man" that negates the Spirit of Prophecy, or the core beliefs of the church. This opens them to question Adventist theology so they look for a variation and some find it and start to follow those like Desmond Ford who use the message of righteousness by faith to try make null and void the scriptures understanding in Adventist foundational doctrines and thought. Once their faith is influenced by this line of thought then the person starts to look for 'cracks' in the Adventist theological so they can justify their rejection of the church and/or their leaving.
They will claim that Adventists follow the gospel of Ellen White rather than Jesus Christ. They feel they are following the original stream of the Protestant Reformation view of the Bible and the Bible only as the only authority in testing the theology of Adventism and that any new light from inspiration even if in harmony with the Bible is a corruption of "truth". They will look for issues with or attack the tried and true texts in the word of God by calling it faulty or not to be understood, they will bring up the charge or 'prooftexting' such as that Adventists use the KJV so they can give the verse, “Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.” Rev. 22:14, which supports Adventist thought. They also will tend to have a issue with Rev 12:17 and 19:10 that reveal that one of the distinctive marks of the remnant church is the Spirit of prophecy. As Adventist well know, Rev 12:17 says that two distinct marks of the remnant seed of God's church is that they 1) keep the commandments of God and 2) have the testimony of Jesus. Among churches that keep the Sabbath, the SDA church is the only one that has a prophet. Among churches that claim to have a prophet, the SDA church is the only one that keeps the Sabbath, so they must destroy faith in the Spirit of prophecy before they can fully get at the belief in keeping the commandments. They claim it is easier to “prove” Adventist theology from the KJV so they try and make a case for other "better" translations. With some of these "newer" or more "contemporary" translations it sometime changes the words such as "Commandment", "Sabbath" and many others which Adventist know by heart to a more obscure reference so it hides the true meaning, but this is used as proof that the understanding by Adventist theologians is faulty.
Then they go after the authorship and words of Steps to Christ, Great Controversy, etc... Soon they find justification to go after the author herself to destroy any belief in any of the light that she shines, they must wipe out any of the direction or expansion on the scripture and prophecies that she gives, as they must wipe out all belief in her role as a messenger of God to justify to their apostasy.
Eventually those that are walking down the steps to apostasy then reach a point when they must decide on Ellen White. Either she was a true prophet, or inspired "messenger of God" or she was not. If she was, then they know they must return to Adventism for she repeatedly stressed the church would not fall and there would be a remnant at the end and that those who leave the Adventist church and turn against it are endangering their souls. So they must justify their apostasy by claiming she was not, then they dont need not be bound by her many statements on those who turn against Adventism.
This is no little matter for Adventists. It must be resolved. Point number 17 in the Fundamental Beliefs of Seventh-day Adventists states:
"One of the gifts of the Holy Spirit is prophecy. This gift is an identifying mark of the remnant church and was manifested in the ministry of Ellen G. White. As the Lord’s messenger, her writings are a continuing and authoritative source of truth which provide for the church comfort, guidance, instruction, and correction."
They state that problem is that the SDA church has two sources of truth, and though the church claims that the Bible is the standard, in practice it is usually the Bible interpreted by Ellen White which thus is a corruption.
Then they reach a point where they will attack the Adventist use of the principles of hermeneutics, which deals with the presuppositions principles and of interpretation. They lay the claim that Adventism have taught their members to study the Bible by the “here a little and there a little” method, and that this is the method often used to prove most of the teachings of Adventism. So any teaching of Adventism is corruption and thus they are justified to reject them and leave the church.
It may not follow exactly, but as a rule they find areas to disagree with the beliefs traditionally held by mainstream Adventism and officially by the church and begin to separate themselves from its beliefs using such as terms such as evangelical Adventism, cultural Adventism, charismatic Adventism, and progressive Adventism and others. They will mildly disagree with then build on it till they get to a point where they reject one or more of the church's basic beliefs such as the Sabbath or core beliefs such as the investigative judgment, the remnant, a future global Sunday-law, or a use of Ellen G. White's writings. They also tend to question some of the denomination's 28 fundamental beliefs: with debate arising on the nature of the Trinity, perpetuity of the Law of God, the Nature of Christ, the Gift of Prophecy, Creation or observance of the seventh-day Sabbath.
You will find that the complaints against Ellen White, hold little merit or the sum of them are trivial in nature or nit picking to say the least. The part which then seems to evolve and become another force pushing them away and you noticed soon that is the most powerful for deception is the false idea of what righteousness by faith is. They build on the idea that behavior has no significance in our lives anymore. They always say that it is not a license to sin but then out of the corner of their mouths they essentially infer it doesn't matter what you do or even if you repent or confess or not, you will be saved. This drift takes them down to the danger which is once saved always saved at it's core even though they deny it.
They then are fully open to the deceptions of even worse snares with another stream from the ecumenical emerging church movement, such as spiritual formation or disciplines. Soon rather than come to church, they are satisfied to just gather in small groups who believed as they do. Or building on the idea that the Sabbath doesn't matter or any day is ok, they being to go to other Sunday keeping churches like those with formed on the Willow Creek model. However, eventually they become embittered against Adventism, and you have never seen such vengeful vitriol as will find coming from former SDA's. In some who go this path, there is a good case for saying they actually hate Adventism with a passion, with a unexplainable bitterness.
I have seen those who use these steps and it always seems to lead to rejection of and leaving the church at its end point, now the problem is once they leave where do they go. Many when they reach this stage, see the truth they have left and the corruption they are embracing and I feel sad as it seems prides seems to show itself and they wont take any counsel at this point, yet feel they are heading somewhere, they just don't know where.
This is a problem that Adventist and the church have yet to truly solve, as we see these souls either following this path against the church and its members or completely letting go of all belief, or worse turning against God and any religion grasping spiritualism or even as I have seen to the occult or other vehicles of belief against God.