JS side :

$('.auth_td').on( "click", "#log_in_button" , function(event) {
                       event.preventDefault();
                       var name_field = $('#name_field') ;
                       var password_field = $('#password_field') ;
                       var alert_message="";

                       if ((name_field.val()=="")&&(password_field.val()=="")){


                          $("#auth_state_row").text("Please fill name and password field");

                       }
                       else if(name_field.val()=="") {


                           $("#auth_state_row").text("Please fill name field");

                       } else if (password_field.val()=="") {


                           $("#auth_state_row").text("Please fill password field");

                       } else {

                        var csrftoken = $.cookie('csrftoken');
                        $.ajax({
                          type: "POST",
                          url: "/",
                          data: {username:name_field.val(),password:password_field.val(),csrfmiddlewaretoken:csrftoken},
                          success: null,
                          dataType: "json"
                         });

                       }


});


Python Side :


def return_main_page(request):

    html=""

    if request.method=="POST":

        print ('username %s password %s'%(request.POST.get('username',''),request.POST.get('password','')))

        username = request.POST.get('username','')

        data = {'authenticated':True,'username':username}

        return render_to_response('main.html', data)

    if request.user.is_authenticated():

        username = request.user.username

        html = render_to_response('main.html', {'authenticated':True,'username':username})

        return html

    else:

        data = {}

        data.update(csrf(request))

        data['authenticated'] = False

        html = render_to_response('main.html', data)

        return html


Добавил в темплейт main.html следующую запись :

{% csrf_token %}