I finally found the answer to this and am posting it here in case someone else needs the answer. Just put the following in your theme file.
<?php
global $post;
$variable_name = get_post_meta($post->ID, 'custom_metaBox', true);
echo html_entity_decode( $variable_name );
?>
Change the variable name and custom_metaBox to your specific values and voila, functioning HTML code.