Precision, clarity and consistency are always important when it comes to discerning the difference between true and false doctrine. It is never enough to accept a view as sound just so long as it is presented with the right words and phrases. The crucial issue is what those words and phrases mean, and whether they are being used in a way that they have been historically and biblically understood.
The question of motives is secondary, but still important. After all a man may be sincerely deceived in the views that he holds, or he may be a deceiver. The primary question is "but what does this teacher mean when he says that he believes in justification by faith alone?" "What does he mean when he says that he believes that God is omniscient?"
The protestation of orthodoxy, and adherence to the confessions, whilst at the same time redefining doctrines smacks of heresy. Departures from the truth are grievous. But departing from the truth by the redefinition and retaining of confessional language is insidious.
Or as Irenaeus of Lyon put it:
"Lest, therefore, through my neglect, some should be carried off, even as sheep are by wolves, while they perceive not the true character of these men--because they outwardly are covered with sheep's clothing (against whom the Lord has enjoined us to be on our guard), and because their language resembles ours, while their sentiments are very different".