Edgar Pearlstein asks (Fri 7 May 1993) whether the Supreme Court, or
any other government authority, has attempted a legal definition of
religion.

The Universal Military Training and Service Act of 1958 exempted
from the draft those whose "religious training and belief" was
opposed to participation in war in any form. It defined "R T & B" as
"an individual's belief in a relation to a Supreme Being involving
duties superior to those arising from any human relation, but [not
including] essentially political, sociological, or philosophical
views or a merely personal moral code."

In the 1965 case of UNITED STATES V. SEEGER, the Supreme Court
broadened the definition so as not to restrict it to explicit

   We have concluded that Congress, in using the expression "Supreme
   Being" rather than the designation "God," .... the test of belief
   "in a relation to a Superme Being" is whether a given belief that
   is sincere and meaningful occupies a place in the life of its
   possessor parallel to that filled by the orthodox belief in God
   of one who clearly qualifies for the exemption. Where such
   beliefs have parallel positions in the lives of their respective
   holders we cannot say that one is "in a relation to a Supreme
   Being" and the other is not...."

My immediate reference is THE FIRST FREEDOM, by Nat Hentoff,
(Delacorte 1980, Dell 1981).