w/Public Domain Clip Art
Religious and Bible Illustrations
B/W Bible Illustrations
The above websites are some sources of free and public domain images. Some of the artwork in these websites may be copyrighted, but very many of them are public domain and free. Just be sure to check the status of the artwork and read the copyright/licensing information before re-using them in your project. Note that some countries have different copyright protection laws. For example, a work of art may be public domain in the US, but not in Mexico.
Even if an image is already in the public domain, it is recommended that the original source or author of an image be credited to give correct provenance.
Some of the artwork displayed in the above websites may contain nudity; so, caution is advised.
Not all images were created by Catholic artists, although many were made by fellow Christians. Also, some images may not be factually correct. Therefore, discernment is advised.