Alicia Silverstone was born to Jewish parents but is not known to be an observant Jew in any religious sense. Alicia Silverstone is a committed Ethical Vegan, i.e., an adherent of the religion known as Ethical Veganism.
From: "Alicia Silverstone" article on Wikipedia website (http://en.wikipedia.org/wiki/Alicia_Silverstone; viewed 19 December 2005):
She is also noted for her strong views on animal welfare and is a committed vegan. In 2004, Silverstone was voted sexiest female vegetarian...Silverstone was born in San Francisco, California, to English Jewish parents Monty Silverstone, real-estate investor, and Didi Radford, a Scottish-born former flight attendant. She was raised in Hillsborough, California.