If, in Step #3, while adding your podcast to a podcast directory, you swapped out an old RSS feed from a different podcast host with your new RSS feed from your Sermon Engine, all the content from your old host will be replaced with the content from your Sermon Engine.
If your old RSS feed is still live (meaning you're still paying for your old hosting platform), people can still subscribe to it, but they won't receive anymore updates to their podcast feed, since that RSS feed is no longer syndicating to that specific podcast directory (Apple/iTunes, Google Play, Spotify, etc.).
But What About My Current Subscribers?
For all current subscribers, if you have their contact information, you can send them the URL to subscribe to your new RSS feed.
Additionally, some podcast hosting platforms will allow you to redirect current subscribers to your new RSS feed. Below are some walkthroughs of some of the more major podcast hosting platforms on migrating from an old RSS feed to your new one. Please note, some of these are written by a 3rd party and will refer to their own podcasting platform (Blubrry).
LibSyn (Start at the heading, Redirecting your Libsyn feed.)
Buzzsprout (Start at the heading, Apply the 301 redirect to your Buzzsprout RSS feed.)
After you've redirected people from your old RSS feed to your new one, it's time for one last momentous step of promoting your podcast on your Sermon Engine!