WordPress function to use with WP-Members plugin. Replaces the post index with a login page. To use, create a page and add the shortcode `[wp-members page="login"] ` to it, then get the ID of that page and put it on line 7 as the value of `page_id`.

functions.php

<?php

//* Replace post index with login page for non-members
function premium_posts_05132014sms( $query ) {
    if ( $query->is_home() && $query->is_main_query() ) {
        if ( current_user_can( 'subscriber' ) || !is_user_logged_in() ) {
            $query->set( 'page_id', '12' ); // Replace 12 with the ID of your login page
            $query->set( 'post_type', 'page' );
        }
    }
}
add_action( 'pre_get_posts', 'premium_posts_05132014sms', 9999 );