Just define faith for them. We have two verses we can place together that give us the complete picture. And that is what we want to emphasize, the COMPLETE picture. So, we have Paul writing that "faith comes by hearing and hearing by the Word of God." And we have James writing that "faith without works is dead being alone." So when we put them together we learn that "faith comes by hearing the Word of God and then ACTING on what we hear." We hear... and then we do... that is faith. Moses was told, "hold out your staff," and he heard and did and the water parted. Noach heard that a flood was coming and that he needed to build an ark. So, he heard and he built and he was safe. Abraham was told to move to a place he had never been before and so he heard and he moved. Hear and do... that is faith. Hebrews 11 is the great faith chapter... and every example has somebody hearing God and then acting on what they heard.
And if anyone wants to argue that... just walk away. One only hears when they are seeking and we can't make another seek!