Just a quick post in case you are trying to use a JSF page as a welcome file. This is what you'll need in your web.xml:

    <servlet>
        <servlet-name>Faces Servlet</servlet-name>
        <servlet-class>
            javax.faces.webapp.FacesServlet
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Faces Servlet</servlet-name>
        <url-pattern>*.xhtml</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>index.xhtml</welcome-file>
    </welcome-file-list>