I have created a sample ASP.NET MVC website in VS 2015 and in a view i am using the extension Ajax.BeginForm to post login credentials to controller, and on OnSuccess callback i
If your displaying only the json returned by your LogIn() method, then its because you have not included jquery.unobtrusive-ajax.js file in your view. As a result, Ajax.BeginForm() falls back to making a normal submit