Humanism simply refers to man-developed, man-based, and man-focused solutions and activities. Whether it is a religion or a spiritual pursuit is a separate issue (does it make Man into his own god?). It is a way of life that strives for independence from religious or god-centered worship and motivations. If it must put up with religion for pragmatic purposes, then humanists will tell you that all religions are equally valid and true, as are all cultures.

Humanist Manifesto I, II, III - American Humanist Society