Martin is the patron of, among other things, mixed-race people. I think even after all this time that and the last lines of John XXII's homily say everything we need to learn from this saint today.
He excused the faults of others. He forgave the bitterest injuries, convinced that he deserved much severer punishments on account of his own sins. He tried with all his might to redeem the guilty; lovingly he comforted the sick; he provided food, clothing and medicine for the poor; he helped, as best he could, farm laborers and Negroes, as well as mulattoes, who were looked upon at that time as akin to slaves: thus he deserved to be called by the name the people gave him: ‘Martin of Charity.’
It is remarkable how even today his influence can still move us toward the things of heaven. Sad to say, not all of us understand these spiritual values as well as we should, nor do we give them a proper place in our lives. Many of us, in fact, strongly attracted by sin, may look upon these values as of little moment, even something of a nuisance, or we ignore them altogether. It is deeply rewarding for men striving for salvation to follow in Christ’s footsteps and to obey God’s commandments. If only everyone could learn this lesson from the example that Martin gave us.
-- Homily on the Canonization of Martin de Porres, John XXIII