Audio or Visual or Both?

The first question to ask is: Do you have the technology and people to do audio or visual or both?

From a technological point of view you'll need a good means to record the audio each week. If you mic up the preacher you might be able to make an audio recording directly from a mixing desk. This is the absolute best option for you.

Failing that, you could invest in a good quality audio recorder. The quality will never be as good as from a mixing desk though. Not only will it record more background noise, if you keep it on the lectern the audio levels will vary if the preacher wanders away from the lectern.

You'll need a decent method to record the video. The best options are video cameras or digital SLR cameras that are able to record sermons in one take (some automatically cut off after a certain amount of time). If you don't have that you could test how good a mobile phone is. Modern phones can be remarkably good.

Audio will be a problem though. Avoid automatic sound recording levels - they tend to over-emphasise background noise when there's a pause in the sermon, even if only for a second.

For the very best video results

Take the audio feed from the mixing desk and replace the audio from the video camera. Be warned - this is an advanced task adding around an hour or so to the workload of putting up videos each week.