99% of the times that you should not use audio in a PowerPoint presentation. You can take your 1% and plug it into your slide show . . . but before we get there, another word on using media in your presentation.
Be prepared for it to not work. No matter how much you work and practice and test there will come a time when your clip doesn't play. Maybe the speakers aren't hooked up or the file doesn't get transferred or gremlins eat the audio file. Something will happen to make the media not play. You have to be ready for this to happen and to move on. Keep a printed copy of the quote you were going to play so you can just read it aloud. Don't wait for the sound guy more than about 10 seconds. Don't fret and say to the audience that you're having technical difficulties. Pause for your audio clip and look at the audience with a confident smile. If the clip doesn't play, then smoothly move on with your sermon.
If the clip starts playing after you've started talking again, then just stop and wait for the clip to finish. If the topic warrants you might make a small joke: "No one ever accused ______ of being punctual." Then move on again. Don't apologize. Don't derail. Keep your point moving forward.
Are you scared of putting audio in your sermon yet? Good. It's a lot of hassle and a lot of risk, so it has better be worth it.