Luke 8:18 Take heed therefore how ye hear: for whosoever hath, to him shall be given; and whosoever hath not, from him shall be taken even that which he seemeth to have.
Why are people going back from previous and well established understandings of the Bible such as the 'end of the Church Age' doctrine and the 'faith of Christ' doctrine and the 'Sunday Sabbath' doctrine? The Bible presents one very simple reason for this, in the Day of Judgment God takes away from the unsaved professed 'true believer' that which they seemed to have. That is, they seemed to have salvation because they possessed, for a time, a right understanding of faithful Bible doctrines.
Matthew 25:28 Take therefore the talent from him, and give it unto him which hath ten talents.
29 For unto every one that hath shall be given, and he shall have abundance: but from him that hath not shall be taken away even that which he hath.
30 And cast ye the unprofitable servant into outer darkness: there shall be weeping and gnashing of teeth.
In these days after the tribulation, during this prolonged judgment period, the Lord is actively taking away the things they previously had gotten right. For some, it started right at the very beginning of Judgment Day, they went backwards in understanding regarding the Biblical calendar of history and the date locked in by God for judgment (May 21, 2011). The unraveling has continued ever since. We can expect to see more of the same in the future. During the time period in which the final judgment is carried out the actual condition of their heart surfaces and becomes more obvious as God takes away their understanding of truth and allows them to now believe errors that more accurately reflect their unsaved condition.