“Truth and Heresy” (1649) by Wesminster divine George Gillespie is an excellent piece warning about doctrinal compromise and deception. The following is an excerpt refuting the theological relativists of his time, who are not unlike those of today:
“Search the scriptures,” John 5:39; Acts 17:11. Do not take upon trust new lights from any man, be he never so eminent for parts or for grace, but to the law and the testimony.
The upshot of all is that we ought to hold fast the profession of our faith without wavering, and be steadfast, and even immovable in the truth, and not to give place to the adversaries, no, not for an hour, Gal. 2:4-5.
I do not mean pertinacity in the least error, nor a vain presumptuous overweening conceit of our knowledge, to make us despise any light which others may give us from scripture. Pertinacity is an evil upon the one hand, and to be too tenacious of our own opinions; but that [Gk.] kenotas [emptiness] and [Gk.] kouphotas [lightness], that levity, inconstancy, wavering, skepticism, is an evil upon the other hand. “Be not soon shaken in mind,” etc., 2 Thess. 2:2.
And this is the epidemical disease of the sectaries of this time, which I have now been labouring to cure. Their word is yea and nay, and not unlike to that which Sallust objected to Cicero, that he said one thing sitting, another thing standing. Yet it may be sometimes observed, that those who are the greatest skeptics and Pyrrhonians in reference to the common and received tenets are the most pertinacious and tenacious in tenets invented by themselves.
I have read it observed of Socinus, that as he set at nought fathers, councils, and the whole current of ancient and modern interpreters of scripture, so vain glory made him to maintain stiffly and tenaciously any opinion or invention of his own, as if he had been infallible.