King James Onlyists have a habit of making much out of what are actually rather minor differences between the KJV and other Bible translations. In most cases, the two turn out to actually be saying the very same thing, just in different words. Many other times, the difference is real, so far as it goes, but is actually only a matter of specificity. One translation will use a word or phrase that can be read more broadly while the other will be more narrow and precise, but the broad meaning contains the narrow one within it. For example, if one translation were to say that a man was attacked by wolves and the other by wild beasts, these translations would be different but they would not be in conflict. Wolves are wild beasts. One version is simply more precise, the other allowing that the Greek or Hebrew word may have been referring to some other kind of hostile animal. This is exactly the kind of difference we find in Titus 3:10. Since some King James Only advocates make much of this passage, it is worth examining.
Versions of the Verse
The verse in question reads as follows:
"A man that is an heretick after the first and second admonition reject," (Titus 3:10, KJV).
"Reject a factious man after a first and second warning," (Titus 3:10, NASB).
The difference here lies in what sort of man Paul is telling Titus to reject. Is he referring to a heretic or a factious man? Most modern translations basically agree with the NASB here, just with different wording. The ESV, for example, says a "person who stirs up division," while most others read a "divisive man".1 Interestingly, a few of the pre-KJV English translations of the 16th century had a reading somewhat in the middle, speaking of "a man that is an author of sects."2 As noted above, these readings are not really contradictory but rather vary only in specificity. Heretics are sectarians, but not every "author of a sect" is necessarily a heretic. A sect or faction may be entirely orthodox in doctrine but divide for other reasons. In the same way, all sectarians are divisive, but a man might be divisive without authoring a sect. What we have in these terms are concentric circles, with the broader terms containing the narrower ones. None of these translations contradicts the others, some are simply more general and allow a wider application than others.
Changes in Language
So far, all of this assumes that the word "heretic" meant then what it means today. In actual fact, the word "heresy" was itself a broader term in the 16th and 17th century than it is now. It referred to any teaching or practice that was considered divisive or sectarian, not merely to the sort of gospel-compromising false teaching we would call heresy today. Thus, back then, beliefs by orthodox denominations could be considered "heresy" even though they did not deny the gospel or the nature of Christ or any other issue directly related to salvation. Instead, their views were considered "heresy" simply because they necessarily divided that denomination into their own separate churches. "Heresy" was any teaching or practice that divides or factionalizes. This includes the sort of damnable doctrines we call heresy today, but it is not limited only to such things. Thus, even the KJV's wording may actually be broader than it at first appears, and indeed may not really differ at all from the NASB's "a factious man."
Addressing the Difference
As one can hopefully see by this point, our question here is not, strictly speaking, whether it is the KJV or the modern version that is accurate. Both are. All of them include the same basic meaning. The question is merely one of scope. Just how specific did Paul himself intend to be? Was he speaking only of those whom we would call "heretics?" Was he focusing here exclusively on those who profess pernicious false doctrines that compromise central beliefs on matters such as the nature of God and the Gospel? Or was the focus broader than that?
The Greek word in question here is αἱρετικός. The word itself simply means "pertaining to causing divisions; factious, division-making." Thus, the renderings found in modern versions like the NASB or ESV are quite literal and straightforward to the meaning of the word itself. Of course, just how Paul was using the word here is best defined by the context. The verse before seems to provide a range of the kind of "divisive" man that Paul had in mind. There, we read:
"But avoid foolish questions, and genealogies, and contentions, and strivings about the law; for they are unprofitable and vain," (Titus 3:9, KJV).
"But avoid foolish controversies and genealogies and strife and disputes about the Law, for they are unprofitable and worthless," (Titus 3:9, NASB).
Here we see that Titus is being instructed to avoid not only flagrant false teaching that compromises the faith, but also worthless contentions and the like. Even matters that may not be "heresy," in the strictest sense, but that needlessly divide or create controversy within the body are to be avoided. Thus, it seems that the modern rendering of "divisive man" or "factious man" best captures what Paul has in mind. The KJV's wording, while not incorrect, is a bit too narrow (at least in the word's current usage today) and thus risks missing some of what Paul had in mind. Thus, while the KJV provides a fine translation here, more recent translations better capture the totality of Paul's point for modern readers for whom "heretic" has a much more specific meaning.