And their word - The word, or the discourses of those who love vain and idle disputations.
Will eat as doth a canker - Margin, “gangrene.” This word - γάγγραινα gangraina - occurs nowhere else in the New Testament. It is derived from γραιω graiō, γραινω grainō, to devour, corrode,” and means “gangrene” or “mortification” - the death of a part, spreading, unless arrested, by degrees over the whole body. The words rendered “will eat,” mean “will have nutriment;” that is, will spread over and consume the healthful parts. It will not merely destroy the parts immediately affected, but will extend into the surrounding healthy parts and destroy them also. So it is with erroneous doctrines. They will not merely eat out the truth in the particular matter to which they refer, but they will also spread over and corrupt other truths. The doctrines of religion are closely connected, and are dependent on each other - like the different parts of the human body. One cannot be corrupted without affecting those adjacent to it, and unless checked, the corruption will soon spread over the whole.
Of whom is Hymenaeus and Philetus - In regard to Hymenaeus, see the notes at 1 Timothy 1:20. Of Philetus nothing more is known. They have gained an undesirable immortality, destined to be known to the end of time only as the advocates of error.