With the coming of the Ptolemaic dynasty to the Egyptian throne, the goddess Isis goes through a series of changes that will turn her into a very different divinity. This new Hellenistic or Greco-Roman Isis not only stands out for the degree of expansion attained throughout the Mediterranean world but also for displaying a series of attributes,
... among which we highlight one in particular: Her role as goddess of the Sea. This not only changed the attitude of her devotees but also entailed deeper ritual implications, festivities and iconographic motifs. There are innumerable variations that brought about her “metamorphosis” into a maritime deity, especially since this was one of the most popular facets of Isis that penetrated the Roman Empire.
In adopting a foreign cult, ancient Roman worshippers were not searching for a new religion to replace their old one, but rather seeking to expand the range of gods and practices at their disposal. They assumed that all traditional gods and religions were valid and effective. There was, therefore, an implicit toleration built into the system of
... ancient polytheism, and this was admired by the thinkers of the Enlightenment, though the Roman state never guaranteed freedom of worship. The cult of Isis was distasteful to the Roman élite, and the government often reacted brutally to particular actions by her worshippers. Nevertheless, her cult was always popular with the general public and the state never wished to abolish it, and eventually built a public temple to Isis. The worshippers of Isis tested the limits of Roman toleration and demonstrated its vitality.