Update you code with this
<?php // Output all Taxonomies names with their respective items
$catCount = 0;
$terms = get_terms('sermon-series');
foreach( $terms as $term ):
?>
<div class="sermon_title_area">
<h3><?php echo $term->name; // Print the term name ?></h3>
<div class="sermon_date">
<p><?php echo $term->description; ?></p>
</div>
</div>
<div class="flexslider carousel">
<ul class="slides">
<?php
$posts = get_posts(array(
'post_type' => 'sermon',
'taxonomy' => $term->taxonomy,
'term' => $term->slug,
'nopaging' => true, // to show all posts in this taxonomy, could also use 'numberposts' => -1 instead
));
foreach($posts as $post): // begin cycle through posts of this taxonmy
setup_postdata($post); //set up post data for use in the loop (enables the_title(), etc without specifying a post ID)
?>
<li>
<div class="slider_contents">
<a href="http://www.youtube.com/watch?v=<?php echo get_field('youtube_video_link'); ; ?>" rel="prettyPhoto" title="<?php the_title(); ?>"><?php the_post_thumbnail('slide-image', array('class' => 'slide-thumb')); ?></a>
<div class="slider_inside">
<h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
<div class="date">
<?php the_time('F j, Y'); ?>
</div>
<div class="excerpt_contents">
<?php echo excerpt('10'); ?>
</div>
<?php if ( get_field('mp3_link') ) : ?>
<div class="download_link">
<a target="_blank" href="<?php echo get_field('mp3_link'); ?>">Get the MP3 >></a>
</div>
<?php else : ?>
<?php endif; ?>
</div>
</div>
</li>
<?php endforeach; ?>
</ul>
</div>
<?php
$catCount++;
if($catCount == 2)
{
echo '<a href="'.get_term_link($terms{2}->term_id, $term->taxonomy).'">Next</a>';
}
endforeach; ?>