No. That would be bad. I'm assuming you're using JomSocial 1.8.7, but this should be similar for most versions of JomSocial. To replace that Facebook Login button, you would want to edit tmodify the frontpage.guests.php template file from JomSocial. The file can be found /components/com_community/templates/default/frontpage.guests.php file, but you should use a template override for this file (see below). That file defines the top portion of the home page when a user isn't logged into your site.
At the very bottom, you'll see:
<?php echo $fbHtml ?>
Try removing that code and replacing it with what's above. Add the <?php and ?> around it so that it executes (and doesn't just display on the page).
We haven't tested this directly recently, but this should do what you're looking for.
For more information on Template Overrides, please read the following:
www.sourcecoast.com/extensions/troublesh...s#template_overrides