Because there is an issue with OAuth2 login and localhost development, you currently have to deploy your meteor site to be able to test the Facebook login. A nice little workaround for this is to make the local instance of meteor accessible externally.
There is a great online guide for setting up port forwarding with your router and you can check your public external IP here.
For example, If you have an Apple router, simply open up Airport Utility on your Mac and click edit on your router, then go to the Network tab. Under Port Settings click the + icon and select Personal Web Sharing, setting all of the public and private ports to 3000. Make sure the private IP is set to your current computer IP.