Hello, user sets itself after reloading the page

public ActionResult HomePost(Home model)
    {
        if (ModelState.IsValid)
        {
            FormsAuthentication.SetAuthCookie(model.Topic, false);
            var user = User.Identity.Name;
            return View("Home", model);
        }
        //Do some stuff here, then return the base method
        return View("Home", model);
    }