And many shall follow their pernicious ways; by reason of whom the way of truth shall be evil spoken of. Many shall follow - Will follow, because determined to gratify their sinful propensities.
Pernicious ways - Ταις απωλειαις· Their destructions; i.e. the heresies of destruction, or destructive opinions, mentioned above. But instead of απωλειαις, destructions, ασελγειαις, lasciviousnesses or uncleannesses, is the reading of ABC, and upwards of sixty others, most of which are among the most ancient, correct, and authentic. This is the reading also of both the Syriac, all the Arabic, the Coptic, Ethiopic, Armenian, Slavonic, Vulgate, Chrysostom, Theophylact, Ecumenius, and Jerome. A very few, and those of little repute, have the word in the text.
The word lasciviousnesses is undoubtedly the true reading, and this points out what the nature of the heresies was: it was a sort of Antinomianism; they pampered and indulged the lusts of the flesh; and, if the Nicolaitans are meant, it is very applicable to them, for they taught the community of wives, etc. Griesbach has received this reading into the text.
By reason of whom - These were persons who professed Christianity; and because they were called Christians, and followed such abominable practices, the way of truth - the Christian religion, βλασφημηθησεται, was blasphemed. Had they called themselves by any name but that of Christ, his religion would not have suffered.