Religious Freedom for Providers of Adoption, Foster Care, and Child Welfare Services Act - Amends the Social Security Act to prohibit federal payments for foster care and adoption assistance to a state or local government that discriminates against any entity that provides adoption or foster care services to only those couples who are united in marriage (defined as a legal union between one man and one woman as husband and wife) and to only those individuals whose conduct is in accordance with such entity's religious principles and practices.