Better fix

app/helpers/activities_helper.rb

 module ActivitiesHelper
   def require_organizer!
-    require_login!
     if !@activity.may_change?(current_person)
       flash_message(:danger, I18n.t('authentication.organizer_required'))
       redirect_to group_activity_path(@group, @activity)

app/helpers/authentication_helper.rb

     if !is_logged_in?
       flash_message(:warning, I18n.t('authentication.login_required'))
       redirect_to controller: 'authentication', action: 'login_form'
+      return false
     end
+    return true
   end
 
   def require_admin!

app/helpers/groups_helper.rb

 module GroupsHelper
   def require_membership!
-    require_login!
+    return unless require_login!
     if !(@group.is_member?(current_person) || current_person.is_admin?)
       flash_message(:danger, I18n.t('groups.membership_required'))
       redirect_to dashboard_home_path
   end
 
   def require_leader!
-    require_login!
+    return unless require_login!
 
     if !(@group.is_leader?(current_person) ||
          current_person.is_admin?)