In a sense, you are correct, for faith is the fuel that energizes the believer to work towards the object of their belief.
One can believe without acting upon it. Faith is in evidence only when the believer ACTS upon their belief.
After the laborer receives pay for work completed, it is not necessary to continue to labor for wages already earned. So, upon payment of wages, the laborer no longer is required to believe they will get paid -- having the fruits of their labor (faith) in hand.
One who has received wages has received proof that their labors (faith) were justified, and are henceforth, 'knowers,' -- having passed beyond the 'belief' stage.
It is difficult for one to share 'proof,' but easier to share the fruits.
Seems to me, since it is basically a fact (You can't have "Faith" once something has been proven...You don't need it anymore), I would use that as my argument in your position. It's so simple and direct. Not to mention, unarguable.