From the pen of Samuel Miller regarding the growth and development of false teaching and heresy,

When heresy rises in an evangelical body, it is never frank and open.  It always begins by skulking, and assuming a disguise.  Its advocates, when together, boast of great improvements, and congratulate one another on having gone greatly beyond the “old dead orthodoxy,” and on having left behind many of its antiquated errors: but when taxed with deviations from the received faith, they complain of the unreasonableness of their accusers, as they “differ from it only in words.” This has been the standing course of errorists ever since the apostolic age.  They are almost never honest and candid as a party, until they gain strength enough to be sure of some degree of popularity…

They denied their real tenets, evaded examination or inquiry, declaimed against their accusers as merciless bigots and heresy-hunters, and strove as long as they could to appear to agree with the most orthodox of their neighbors; until the time came when, partly from inability any longer to cover up their sentiments, and partly because they felt strong enough to come out, they at length avowed their real opinions…”

This was written in reference to Jacob Arminius‘ error in the 16th and 17th centuries and the way the Dutch churches did not immediately call them to account in discipline and work to stop the error through broader assemblies.

It is not surprising that our day and age is rife with this reality, even more so with the immediate ability to peddle heresy to unsuspecting multitudes.  Isaiah 8:20, “To the law and to the testimony: if they speak not according to this word, it is because there is no light in them.”