Context. If you know the history then it’s obvious who it is.
Abelard is a very, very good guess, and I thought it had to right (and perhaps it is — see below). As it turns out, the illustration is from “Favole libertine” with 12 illustrations by Milo Manara, inspired by the erotic stories by Jean de La Fontaine”:
I am not familiar with Jean de La Fontaine, so ... maybe one of the stories concerns the story of Abelard being tempted by a trollop. Or maybe it’s just some generic monk.
Whatever, it clearly depicts a monk resisting a female temptress, not Jesus. He is wearing a monk’s robe with knotted cord.
As you can see, this image was very popular among meme makers long before Musk used it:
https://tineye.com/search/928ab603ebb3c3e34e5134290f2997c9f02e22c7?sort=score&order=desc&page=1
Manara is predictably a lefty and has responded to Musk:
https://www.comicsbeat.com/milo-manara-claps-back-at-elon-musk/?amp
The things one can learn from TinEye.
Heloise’s uncle would say Abelard didn’t pray enough.