Simulate the_content() with a WordPress shortcode.

wp-old-content-debugger.php

<?php
/**
 * Set up faux the_content() simulation
 *
 * You can use this to simulate the_content() through a shortcode. Simply
 * add the shortcode [faux] on any page in wp-admin and publish. Then,
 * Then, make all your changes in your favorite text editor in the includes/faux-content.php
 * file. Once finished, paste the contents of includes/faux-content.php into the page in wp-admin.
 */
function faux_the_content_() {
	$content = file_get_contents(get_bloginfo('template_url').'/includes/faux-content.php');
	$content = apply_filters('the_content', $content);
	return $content;
}
add_shortcode('faux', 'faux_the_content_');