Humanism vs. Existentialism

We have talked about Heidegger's stance on Humanism and Existentialism; and later we discussed Sartre's idea as well. Jean Paul Sartre's existential philosophy is sort of summarized in the often repeated quote by philosopher Protagoras: “Man is the measure of all things; of things which are, that they are, and of things which are not, they are not.” Existentialism, ultimately, holds man responsible for his condition in the world, and places the weight of the world on the shoulders of man. Even Kierkegaard, who believes in the absolute, seems to hold the previous as true when he references that Abraham had a choice, and it was his complete faith that led him to follow God and his own decision.

The philosophy of humanism similarly declares that the value of man, and the value of life, is a committed search for moral values and truth by virtue of man for the virtue of man. Yet at times throughout Existentialism and Human Emotions, Sartre denies the assertion that existentialism is a form of humanism in the commonly perceived sense of the word, while continuing to push his assertion that deep in the roots of existentialist philosophy lies a true form of humanism that in fact holds man to be the measure of all things. But what exactly are the links between existentialism and humanism, and the differences between the two? Could it be suggested that at their foundation existentialism and humanism are essentially one and the same?

Sartre as we know says that Existenialism is a humanism; and Heidegger says it is not for the sake of his dasein definition. All of the philosophers we have read believe in total uniqueness of man, does that help to connect existentialism and humanism? What do you think?