How did the Persian Empire influence religion today?

After the Persian conquest of Babylon, the Persian king allowed the Jews to return to Judah if the wished to do so. Without this concession, the Jews may have simply merged into the foreign cultures and disappeared as a separate ethnic group, as the Israelite exiles had done before them.

The Persians funded the rebuilding of Jerusalem and of the Jerusalem Temple. They encouraged Judaism, and sent Ezra to teach the Jews their own religion, which must have fallen into disuse during the Babylonian Exile. The Persian eunuch, Nehemiah, saw that the sabbath was not being observed and enforced it.

The Jewish faith evolved rapidly during the Babylonian Exile and the Persian period that followed. Some scholars say that much of this evolution resulted from its absorption of concepts and doctrines from the ancient Persian religion, Zoroastrianism.

The Persians effectively rescued Judaism, from which modern Christianity and Islam eventually emerged.