Our secular society cannot perceive the fullness of liberating truth from a mere visual display of doing what is just. A faulty concept of each person having their own "individual truth" allows the dismissal of such witnesses as examples of good deeds or random acts of kindness. Perhaps a cross around the neck may testify to some Christian sentiment in the eyes of the unbeliever, but in their eyes it is merely a sentiment that will not fit the "truth" of their lives. That false "truth" is held by those in bondage to what Pope Benedict XVI calls the tyranny of relativism, and the Catholic is called to resist that enslaving tyranny.
So then, if liberation comes from knowing the truth, and if faith comes only after hearing, there is a necessary use of words to untangle the web of misperceptions held by the unbeliever. Consider the words of the Lord spoken through the Prophet Isaiah:
Come now, let us reason together,
says the LORD:
though your sins are like scarlet,
they shall be as white as snow;
though they are red like crimson,
they shall become like wool.
~Isaiah 1: 18
It is the work of the Lord to invite sinners to come back to reason. In conformity with our Lord, we must recognize that even in the most unreasonable sinners, the faculty for reason still exists though warped by sin. A gentle invitation back to the table of reason must be extended for the sinner to come to repentance. And this invitation must be spoken by the reasonable, who will be there to aid the sinner out of his or her lack of reason.