أَغَيْرَ اللَّهِ تَدْعُونَ
Do you call upon someone other than Allah?
Inkār uses interrogative form to repudiate an action, belief or proposition. A-ghayra Allāhi tadʿūn challenges invoking any besides Allah; it is not merely a request to identify the invoked party.
Depending on context, denial may overlap with rebuke or surprise. These pragmatic categories are not always mutually exclusive, but denial specifically marks a rejected or disapproved proposition.