The case you want is Employment Division, Department of Human Resources of Oregon v. Smith, 494 U.S. 872 (1990). In that case, the Supreme Court said that although states may accommodate religious practices and beliefs, they do not have to do so. The First Amendment’s requirement is that they not target those beliefs/practices, but they do not have to accommodate them. A neutral law neutrally applied may have a disparate impact on religious groups, but that is permissible.
