Sorting categories by the post date of the entries related to them
Alan,

Without having tested this, you might get the desired result by using the group filter.

So, get all you entries ordered by dateCreated, and then group them by category:

{% set sermons = craft.entries.section('sermon').order('dateCreated desc').limit(null) %}
{% for category, catSermons in sermons | group('categoryFieldHandle.first().title') %}
    &lt;li&gt;{{ category }}
        {% for sermon in catSermons %}
            &lt;li&gt;{{ sermon.title }}&lt;/li&gt;
        {% endfor %}
    &lt;/li&gt;
{% endfor %}


Let me know if that works!