From Thomas Cahill's book, The Gift of the Jews, why has the Babylonian Exile been so significant in Jewish religious history?

Until the time of the Babylonian exile, Jewish religion dictated that worship had to center around the Temple in Jerusalem.  One of the most important aspects of their worship involved animal sacrifices, which could only be performed at the Temple.  When the Babylonians expelled the Jews from Jerusalem, they also destroyed the Temple.  The scattered exiles had to change their traditional worship forms in order to maintain their religious identity.  Some of the major changes...

Until the time of the Babylonian exile, Jewish religion dictated that worship had to center around the Temple in Jerusalem.  One of the most important aspects of their worship involved animal sacrifices, which could only be performed at the Temple.  When the Babylonians expelled the Jews from Jerusalem, they also destroyed the Temple.  The scattered exiles had to change their traditional worship forms in order to maintain their religious identity.  Some of the major changes included the rise of synagogues for worship, a shift to a study of the Torah, and a rise of a clergy class of rabbi to lead worship in diverse locations.  

The destruction of the Temple can not be over-emphasized in Jewish religious history.  The first temple, built by Solomon, was destroyed by these Babylonian invaders led by Nebuchadnezzar around 586 B.C.  A second Temple was dedicated in 515 B.C. but was added upon and expanded until officially recognized in 20 B.C.  This second Temple was destroyed by the Romans in the year 66.  The Jewish Temple in Jerusalem has not been rebuilt since two Muslim shrines now stand on the Temple Mount.  These events are significant because of the strong belief in Jewish faith that the re-building of the Temple is still critical to their continued effective reverence for Jehovah God.