This is a response to volume 4, Holly Card Number 8 ("Question for Cliff")...
Humanism was initially a reaction to the narrowness of medieval life. In the Renaissance (perhaps as a result of the changing economy) the humanists wanted to regain the old Greek and Roman ideals about civic virtue and the cultivation of the self. The Romans called the education into these virtues "humanitas", and thus the name.
Essential to the humanists was the idea that man had value, that it was right to be proud of achievement, and that being educated enhanced man's dignity. Early works of the humanists were such things as Pico della Mirandola's "oration on the dignity of man".
However, all the early humanists were devout Christians. They were certainly criticized in the Reformation period for making too much of man and too little of religion, but they were not thought to be anti-Christian. Their ideas continue today in the guise of a humanities program or education.
In the sense that you are interested in, humanities vs. religion, I think that it is an outgrowth of the Enlightenment period. At the outset of the Enlightenment, people thought religion could be done by reason - not by revelation. When science (especially Evolutionary biology) undermined that idea, a fundamentalist reaction set in. The antagonism between humanities and religion is as outgrowth of that...
More recently, the current bugbear of the religious right, secular humanism, is taken to be the view that man does not need god for values or anything else. Man gives himself values and is independent of god. The 'god is dead' movement is in this vein.
I hope that helps. If not, please give me another chance.