If I understand correctly, you want to make sure they are logged in through Facebook before showing any content?
After having a quick browse through the Administrators and Developers guide I think you should be able to use a Sitecore Rule
.
Your Condition
would be where the current user is connected to the specific social network
, where you set 'specific' to Facebook. This rule comes with the module. Your (custom) Action
could be something like 'Set context item to specific item', where specific item is your login page (keep in mind that you probably want to exclude that page for running the Rule
to prevent infinite loops, assuming your login page is also in Sitecore).
All that's left then is to kick off the rule on page load. To see how Sitecore does this for it's ConditionalRenderingsRules
you can use Reflector, and disassemble the Evaluate
method in Sitecore.Pipelines.InsertRenderings.Processors.EvaluateConditions
.