The Blog page template, part of Cornerstone, allows users to create a page that displays all posts from the site. It also allows the user to filter those posts by a specific category, author, tag, or any combination of these.
Filtering the Blog
Scroll down to the Custom Fields box. If you don't see this box, go to Screen Options on the top right of the page, and make sure the option is checked.
You can add one or all of the following fields: authors, categories, tags.
Each of these fields will accept one or more values to filter the posts by. If entering multiple values, be sure to separate them with commas.