No, despite the confusion with terms often associated with evangelistic religious conversions like "reborn" and "born again."
Rebirthing frequently does enhance an individual's spirituality; but since the effect of Rebirthing is generally to aid the individual in becoming his own authority, so Rebirthing is contradictory to the kind of authority represented by most religions.
Although Rebirthers acknowledge a great benefit from the originator of this breathing technique, Leonard Orr, such affectionate associations do not constitute a cult.