How can my church make sermon content more searchable?

Making a sermon accessible is different from making it searchable. Your sermon is accessible once it is preached; to the degree that somebody can come hear it is the degree to which it can be accessed. Transcription, closed captioning, sign language and braille are all tools that give increased measures of accessibility. 

Making sermon content searchable means enabling a searcher to find content amidst a body of other similar content. So, for example, if a Jonathan is looking for sermons related to "addiction" he will be able to find your sermon entitled, "Fighting addiction by conquering idolatry." But if he is looking for a specific treatment on pornography, he will not find your sermon, because the "pornography" does not appear in your sermon's title, even though you referred to the pornography subject in that sermon. In order to give your sermon the optimal level of searchability, it will need to be transcribed and then posted on your website so that search engines can find the content.

Searchability 101 - post your content online

To recap from the Accessibility page, first get a website, then start a blog on that website, then have your sermon transcribed ideally by a human, but a machine is better than nothing.
Create a new blog post.
  1. In that post, you should make the sermon audio or video file available.
  2. Next to that audio or video file, paste the entire sermon's transcription.
  3. Make the post live and available to the public.
That's pretty much it.  It's a small step, but what a step; transcribing and posting your sermon content not makes your material accessible and searchable, but enables the real power of sermon distribution -- projection.