The state of California recently passed a law — SB1140 — that explicitly states clergy are not required to perform homosexual ceremonies. The law is naturally intended to protect those who might have faced attacks — potentially through equal opportunity or even IRS channels — against religious leaders who act on their faith in opposition to homosexuality:
A person…shall not be required to solemnize a marriage that is contrary to the tenets of his or her faith. Any refusal to solemnize a marriage…shall not affect the tax-exempt status of any entity.
Notably, no law required clergy to act against their faith. The law was a preemptive measure to protect religious freedom — and not from one of the more conservative state governments. Homosexual activists were even “glad” that Governor Jerry Brown “codif[ied] religious protections.”
Via the Religion Clause.