There is a difference between an act done to benefit oneself and acts done strictly for the good of others, even if it is the exact same act. We can fool other people and at times can even fool ourselves, but we cannot fool God. We cannot judge when these Works of Mercy are genuine, and to the recipient it doesn't really matter, however it is readily apparent when they are absent. Where they are absent so too is Salvation.
There is a reason that the Church feeds, shelters, nurses, educates, and serves more people daily than all other organizations combined.
Peace be with you
Your words need to be repeated: We can fool other people and at times can even fool ourselves, but we cannot fool God.
Amazing how some take their life for eternity so lightly and/or on man made teachings - how deliberately evil they are to deceive so greatly. Even Jesus' words and warnings don't register with them!