Under the Mosaic law, the Sanhedrin was “the Jewish senate and the highest native court in both civil and ecclesiastical matters.” The priests of Noah were probably considered to have that same authority. Abinadi is merely reminding them of their role when he asks, why do you “desire to know of me what these things mean?” (v. 25). He then calls them to repentance and asks “what teach ye this people?” (vv. 26–27). Their answer is an affirmation of their need to repent.
To the priest’s response that they teach the law of Moses, Abinadi again calls them to repentance for not living the law they teach (vv. 28–29). Abinadi declares to the priests that they know he is speaking the truth (v. 30). He knew this in the same way that Alma knew the hearts of the people of Gideon: “I know that ye believe them; and the way that I know that ye believe them is by the manifestation of the Spirit which is in me” (Alma 7:17). Although Noah’s priests knew they were not keeping the law, they really didn’t understand the law as Abinadi’s next question revealed: “Doth salvation come by the law of Moses?” (Mosiah 12:31). To their positive response, Abinadi acknowledges the commandments given to Moses on Sinai as a source of salvation (vv. 32–33), but accuses them of not living the first two of the ten commandments given there, nor teaching them to the people (vv. 34–37). He is then interrupted by the king’s reaction.