For years, the rhetoric of substantive neutrality has dominated interpretation of the Establishment Clause. Under this approach, courts and commentators purport to ask whether a public policy under scrutiny is likely to affect religious choices in an unacceptable way. In fact, so broadly has this approach been taken that both separationists and accommodationists resort to it freely, although with radically differing perceptions as to when policy becomes unacceptable. Arguably, however, adherents to this approach have paid insufficient attention to religious behavior per se. Had they paid sufficient attention to this phenomenon, they would have been forced to acknowledge that little of what government does actually affects people's religious beliefs. Moreover, they would have been forced to recognize that vindication of basic human rights will operate as a bar to religious persecution long before such persecution is likely to affect religious choices. In fact, I would argue that a desire to vindicate such rights far more fully accounts for the United States Supreme Court's approach to the Establishment Clause in the mid-twentieth century than any real concern for substantive neutrality.
Salamanca, Paul E., "Quo Vadis: The Continuing Metamorphosis of the Establishment Clause toward Realistic Substantive Neutrality" (2003). Law Faculty Scholarly Articles. 568.