Included since version 3.8 of the theme

iSermons is an exclusive plugin developed to create and manage sermon posts for your website. It is a premium plugin available on Codecanyon at price of $39 but is included with the NC theme for free. To be able to use the iSermons plugin with the Native Church theme, it is recommended that you disable the built in sermons manager from your WP Dashboard => Native Church => Theme Options => Sermon Options

Note: Once the built in sermons manager is disabled, you will not be able to use the page builder or normal widgets ‘(N) Recent Sermons’, ‘(N) Sermon Speakers’, ‘Sermons Albums Widget’ & ‘Sermons List Widget’ won’t work. Also these page templates ‘Sermon Albums’ & ‘sermons’ won’t work anymore. If you are using any of the mentioned widget or page template then make sure you change or delete them.

To use iSermons plugin at it’s best, please see the official documentation here