A painting doesn’t have to have great market value for it to be revered by its owner. You may have an old painting of a relative or ancestor that may be your only visual connection to your family heritage. It may not fetch a good price on eBay or from an art dealer but its value is immeasurable to you and perhaps to generations to come. In that sense, it could be priceless in terms of sentimental or historical value.
Churches often have pieces that require attention. The preservation of religious art is so important.