Facebook and Twitter not posting back to my site. Google+ gives me a 400 error

When commenting using Facebook or Twitter the post does not display on my website after it is submitted. Does this have anything to do with the "Callback URL" (not even sure what this is)?

When I try to log in using my Google+ account, I receive the following:
"400. That’s an error.

OpenID auth request contains an unregistered domain: http://allthingsmarathon.com

Learn more

That’s all we know."

Any assistance with this would be appreciated.