I accidentally had loop inside of the description tag which strangely caused only 17 entries to post to the RSS feed. Below is an example of what was causing the issue:
<description><![CDATA[
{% set speaker = craft.categories.group('speaker').relatedTo(entry).find() %}
{% for name in speaker %}
A Sermon from {{ entry.sermondate | date("l, F j, Y") }}: {{ entry.title }} by {{ name.title }}]]></description>
<category>Podcasts</category>
<category>Christianity</category>
<author>{{ name.title }}</author>
<itunes:explicit>No</itunes:explicit>
<itunes:author>{{ name.title }}</itunes:author>{% endfor %}
After I set it outside the Description tag if gave me all my entries on the RSS feed. Here is my final feed code:
<?xml version="1.0" encoding="utf-8"?>
<rss xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd" version="2.0">
<channel>
<title>Sermons at Example Church</title>
<atom:link href="{{ url() }}" rel="self" type="application/rss+xml" />
<link>http://www.examplechurch.org/sermons/</link>
<description>Weekly morning sermons from Example Church in Sab Diego, CA. For all of our sermon archives, please visit http://www.example.org/sermons.</description>
<lastBuildDate>Sun, 17 Sep 2017 00:00:00 -0600</lastBuildDate>
<language>en-us</language>
<sy:updatePeriod>hourly</sy:updatePeriod>
<sy:updateFrequency>1</sy:updateFrequency>
<itunes:author>Example Church</itunes:author>
<itunes:summary>Weekly morning sermons from Example Church in Sab Diego, CA. For all of our sermon archives, please visit http://www.example.org/sermons.</itunes:summary>
<itunes:owner>
<itunes:name>Example Church - San Diego, California</itunes:name>
<itunes:email>[email protected]</itunes:email>
</itunes:owner>
<itunes:explicit>No</itunes:explicit>
<itunes:category text="Religion & Spirituality">
<itunes:category text="Christianity"></itunes:category>
</itunes:category>
<itunes:category text="Health"></itunes:category>
<itunes:category text="Society & Culture"></itunes:category>
{% if podcastImage.podcastimage|length %}
<itunes:image href="{{ podcastImage.podcastimage.first.getUrl() }}"></itunes:image>
{% endif %}
{% set entries = craft.entries.section('sermonEntry').limit(null).find() %}
{% for entry in entries %}
<item>
<title>{{ entry.title }}</title>
<link>{{ entry.url }}</link>
<pubDate>{{ entry.postDate.rss }}</pubDate>
{% set audio = entry.audio.first() %}
{% if audio %}
<enclosure url="{{ audio.url }}" type="audio/mp3"></enclosure>
{% endif %}
<guid>{{ entry.url }}</guid>
{% set speaker = craft.categories.group('speaker').relatedTo(entry).find() %}
{% for name in speaker %}
<description><![CDATA[A Sermon from {{ entry.sermondate | date("l, F j, Y") }}: {{ entry.title }} by {{ name.title }}]]></description>
<category>Podcasts</category>
<category>Christianity</category>
<author>{{ name.title }}</author>
<itunes:explicit>No</itunes:explicit>
<itunes:author>{{ name.title }}</itunes:author>{% endfor %}
<itunes:keywords>Example Church,Sermons,Christianity,Jesus Christ,Bible Teaching,Discipleship,Service</itunes:keywords>
</item>
{% endfor %}
</channel>
</rss>