Men or women in Temple times, who were precluded from services because of ritual defilement, could, after immersion, alight the Temple mount, enter the house of God and involve themselves in sacrificial offerings and the like. The case of the convert is most dramatic. The individual who descends into the mikvah as a gentile emerges from beneath its waters as a Jew. Immersion in the mikvah can be understood as a symbolic act of self abnegation, the conscious suspension of the self as an autonomous force. In so doing, the immersing Jew signals a desire to achieve oneness with the source of all life, to return to a primeval unity with G-d.
Immersion indicates the abandonment of one form of existence to embrace one infinitely higher.
In our day, in this post Temple period, the power and interplay of ritual status has all but vanished, relegating this dynamic to obscurity. There is, however, one arena in which purity and impurity continue to be pivotal. In this connection only is there a biblical mandate for mikvah immersion - and that is regarding human sexuality. To understand why this is so, we must first understand how the Torah views sexuality. Few concepts have done more harm than this widespread misapprehension.