You could try seeing which sites and pages link to that page and also to that site. There are backlink searchers/checkers available but I don't think they would (be able to) count every single possible hit. Then go onto those blogs and forums and comments sections, etc. and inform them - politely but sternly - that they have not referenced where they got the picture from and request it have a citation added permanently, and also that they are defaming and libelling against Satan, who - as can be seen very clearly - is not evil, etc.; and along with that, providing a not-very-extensive explanation of things, of course with added relevant links (to the page or pages where that picture exists on our sites).
As a part of that, you could also remind them that "priests" have raped Children worldwide and "jesus" appointed them, knowing fully that they would rape them, and christians paying tithes are supporting that international Child-raping, and saying that that is what is evil and has been happening for a very long time, and "jesus" never protected those Children, but instead allowed it to continue and didn't inform the site owner nor site users of that Child rape, which is what actually is evil.
Of course, you could go too far...