From
http://www.nobeliefs.com/exist.htm:
"We have historical people like Hesiod and Plato who mentions Hercules. Similar to the way the gospels tell a narrative story of Jesus, so do we have the epic stories of Homer who depict the life of Hercules. Aesop tells stories and quotes the words of Hercules. Just as we have a brief mention of Jesus by Joesphus in his Antiquities, Joesphus also mentions Hercules (more times than Jesus), in the very same work (see: 1.15; 8.5.3; 10.11.1). Just as Tacitus mentions a Christus, so does he also mention Hercules many times in his Annals. And most importantly, just as we have no artifacts, writings or eyewitnesses about Hercules, we also have nothing about Jesus. All information about Hercules and Jesus comes from stories, beliefs, and hearsay. Should we then believe in a historical Hercules, simply because ancient historians mention him and that we have stories and beliefs about him? Of course not, and the same must apply to Jesus if we wish to hold any consistency to historicity.
...
People consider Hercules and other Greek gods as myth because people no longer believe in the Greek and Roman stories. When a civilization dies, so go their gods. Christianity and its church authorities, on the other hand, still hold a powerful influence on governments, institutions, and colleges."