There are quite a few sites that allow you to use images to use on your website for free. You do NOT want to take images from other church or business websites and use them on your site. That is stealing. If you see an image you want to use from another website, you should write to that site to ask for permission first.
The following sites are the best for free images to use on nonprofit websites:
The following sites are the best for very cheap, high quality images to use on your church website:
The following sites are best for high quality images in which you can buy a subscription to to use on your church website: