Sherem was a very sophisticated and over-confident challenger. How do we know this? He had a substantial and technical vocabulary; he was a very persuasive person. In this verse, it says that he was learned, and that could only mean that he knew the religious tradition in this small world. What else would he have studied? They did not have a chemistry department or a statistics department, but he had a perfect knowledge of the language of the people. Notice that Jacob does not say that he had a perfect knowledge of the language of the scriptures. He may not have known how to read the reformed Egyptian and things like that, but he knew the vernacular; he knew the idioms and what would play well with the people.
In this, he was a little bit like Korihor, who certainly was a demagogue and knew how to raise arguments that sounded good, but that were obviously pernicious and misguided. We read that Sherem "could use much flattery," so he was obviously playing to the crowd. He may have tried to appeal to their wanting to have things plainer, or at least to doing things the more familiar or traditional way.
He was dedicated in some way to the Law of Moses, and he thought that what Jacob was doing was not strict enough or did not follow the correct way of understanding the Law of Moses. He did not oppose the Law of Moses at all. In fact, he thought that Jacob was the one who didn’t understand it quite correctly. However, what his view of the Law of Moses was or what the details of that argument were, we do not know.