How to render the textfield from custom advanced theme setting?
In your template.php preprocess function, you need to pass the message back as a key/value in the variables array. (I set the variable key as "custom_msg" as "message" may be too generic and be accidentally confused with any system message variables"

function MYTHEME_preprocess_page(&amp;$vars) {
    $message = theme_get_setting('message_value');
    $vars['custom_msg'] = $message;
}


Then, in your page.tpl.php, the variable would be accessible as $custom_msg (or whatever custom key you set in the preprocess function) and can be included in your page template as:

&lt;?php if(!empty($custom_msg)) echo $custom_msg; ?&gt;


More information about this can be found on this Drupal.org page: Setting up variables for use in a template (preprocess and process functions)