That whole thing was kinda weird.
You'd think that a just and loving God would have been disappointed in Abraham for saying anything other than "Hell no, I'm not killing my son".
Actually, I think Abraham did think G-d would actually expect him to carry through with it. Rev Shaul (aka Paul to most Christians) was a student of Gamaliel and a student of Talmud. He taught that Abraham believed that G-d would raise Isaac from the dead so that Isaac could still be the fulfillment of the promise. Does this not agree with what you were taught?
In fact, it was the belief that G-d would raise Isaac from the dead if necessary that was credited to Abraham as righteousness.
Shalom.