The Doctrine of the Trinity Act 1813 (53 Geo. III c. 160. sometimes called the Trinitarian Act 1812) was an Act of the Parliament of the United Kingdom. It amended the Blasphemy Act 1697 in respect of its Trinitarian provisions. The Blasphemy Act applied only to those educated in or having made profession of the Christian religion. The Act, passed July 21, was also variously known as the Unitarian Relief Act (Trinity Act), The Unitarian Toleration Bill, and Mr William Smith's Bill, after Whig politician William Smith.