You will find this question in the Shulchan Aruch, 169:2. It says there that if you know that the recipient will not make a Bracha, it is Assur to give food to this person. The Mishna Berurah questions if one can give the food B'Toras Tzedaka. His answer is that one should not withhold the food because of of the Mitzvah of charity.
However, if the recipient would not make a Bracha out of Rish'us (contempt of religious duty - literally wickedness), then one may not give this sinner food. But if it is out of ignorance then one can give the food, probably. Well the average guy would stop here.
But, the Mayshiv Davar states that since today we are faced with a new challenge of Tinuck Shenishba (captured children), i.e. American Jews that don't know enough to know that there is such a thing as a Bracha, we can give food even if we know that a Bracha will not be made, BeToras Mitzva (under the category of a commandment).
Furthermore, one could use Ma'aser money to pay for this poor guy's food as maybe he will be struck by the Torah's view of Chesed even in this day & age!
Look it up, it's good for you.