bbpress Not Showing: How to troubleshoot?

The “most” stripped-down theme I can think of that can run BBPress is just a single index.php file containing:

<?php
// get_header();
if ( have_posts() ) : 
    while ( have_posts() ) : the_post(); 
        the_content();
    endwhile; 
else : 
    _e( 'Nothing!' ); 
endif;
// get_footer();
?>

So my guess is that your while loop is missing something or you are overwriting the the_content filter used by BBPress!

Well, taking the extreme, it looks like it’s possible to run it with the following one-liner in index.php:

<?php the_post(); the_content(); ?>

but that’s just for fun 😉