This is first of all Lee's opinion, and he indicates that he is siding with the Presbyterians on a controversial issue, so it would need to be established that his opinion was shared by the other framers of the Constitution and--more importantly--was the same as that intended by the Bill of Rights. But even if that is granted for the sake of argument, what concept of the "Mahomitan" religion is Lee referring to here? In the context of 18th-century thought, it is most likely he is referring to the widespread Enlightenment opinion that all religions shared a certain set of core values illustrated by, for instance, the parallels between the Golden Rule, the rabbinical version of the Golden Rule, and a parallel Confucian teaching. In any case, he is not referrring to contemporary radical fundamentalist Islam, which did not exist in the 18th century in its current form.