Stag Crown

“Cernunnos is the mysterious, horned deity that was worshiped by Iron-Age Celts across Europe until the end of the first century. Little is known about Cernunnos except his name and his image, which appears on many stone-carvings and other artifacts throughout Europe. He appears crowned with stag’s antlers, is often seated in a meditative position, and is almost always depicted with images of wild animals. Cernunnos is a Roman name meaning “horned one.” He is often associated with Herne the hunter, a character of British folk myth, and the “Green man” of European architecture. Roman invaders associated Cernunnos with the god Mercury. His appearance was eventually adapted as the Christian’s Devil.”

How much of this is true? I’d appreciate facts, not opinion.
thanks~