Here are some depositories where you can find stock photos that are either free or available at a nominal charge:

• www.pexels.com
  This site is completely free. Not specifically Christian-based images, but nice options are available.
• www.lightstock.com
  Great Christian stock images, but not free.
• www.creationswap.com
  Creation Swap offers a variety of free and paid Christian stock images.
• www.unsplash.com
  This site is completely free. Not specifically Christian-based images, but nice options are available.
• www.freeimages.com
  This site is completely free. Not specifically Christian-based images, but nice options are available.
• www.canva.com
  Canva is a great free resource to make creating graphics a little easier with great templates and stock image. You can even incorporate your own logos and images.
• Chamber of Commerce
  Free and easy-to-use tool for stock photography that searches over one million high-quality photos.

Adobe Stock and Shutterstock are also great options. They offer low-cost monthly subscriptions, which may be a good investment if churches are creating high quality content regularly.

On a side note, Google images are not recommended. Copyright issues can be involved and most of the images are very low resolution, resulting in poor image quality.