Seriously. Both because of the talent but also because wtf Mikey don't you want to draw a knight in shining armor or a cow or something.

I'm willing to bet this was assigned to him as part of his training or something, but I don't know that.

On the subject of the content, in actual seriousness, this was a pre-modern, pre-secularized age before the traditionally religious was privatized and viewed as some kind of optional quirky fantasy for adults, subject to taste, one as good as the other. So, moral instruction would have been more overt and crisp, and the subject matter prominent in public. The challenges and difficulties of the moral life would have been taught and spoken of more openly.

I know the OP is joking, but this would be no cause for alarm, as the image is noble in its content. It depicts St. Anthony's triumph over the demonic. It does not glorify the demonic or debase the good.

In this context, Man's fallen state predisposes him toward sin. He is tempted to do things he should not and knows he should not. Add to that the malice and opportunism of the fallen angels - the demons - who, while on a short divine leash, nonetheless can exploit the weaknesses and evil in men to lead them toward their doom. The image would then be received as quite inspiring, perhaps helping to inspire and concentrate the viewer's own efforts to resist temptation, combat evil, and to progress on his own journey of conquering the self.