"There is a Principle which is pure, placed in the human Mind, which in different Places and Ages hath had different Names; it is, however, pure, and proceeds from God. It is deep, and inward, confined to no Forms of Religion, nor excluded from any, where the Heart stands in perfect Sincerity. In whomsoever this takes Root and grows, of what Nation soever, they become Brethren."
Or, the religious experience seen as refractions through a gem. Biases: I'm a sometimes attender of an unprogrammed Quaker Meeting in the American southwest, universalist, and religious humanist. Apply filters accordingly.
Quaker.org is the best Friendly portal. For quick introductions to Quakers, try Facts About Friends, Meeting the Spirit, Quaker Views, Inner Light, or this small FAQ. Faith and Practice a.k.a. The Book of Discipline, which is published by the separate yearly meetings, is as official as it gets; editions from Intermountain, Pacific, Philadelphia, and Britain Yearly Meetings, among others, are online and searchable. I have my own summary of the central ideas. You can find more at Quaker Books. But better than reading is attending—find a North American Meeting near you with Quaker Finder.
For a sense of where this came from, A Quaker Page has historical texts, as does Quaker electronic archive, Quaker Corner, Quaker historical texts, and Quaker Writings. Two interesting e-zines, Quaker Theology and Quaker Universalist Fellowship, have links on theology and universalism, respectively.
Several translations of the Hebrew, Christian, and Muslim scriptures can be found at the Bible Gateway, Ethereal Library, Crosswalk, Qur'an browser, and a few other places. The first ten chapters of Genesis (KJV) color-coded by author may be of interest, as might these annotations and commentaries by skeptics, a list of contradictions, what it says about the poor, and guides to the first and second parts. Better than a translation is reading the Hebrew scriptures in the original (here's a pony). The gist is contained in the 613 commandments.
Ontario Consultants on Religious Tolerance site has many balanced, informative articles on many religions, as do Religious Worlds and (flakily) MetaReligion. BeliefNet can help you choose your religion. The Varieties of Religious Experience by William James is worth close reading. For further study, there's the Encyclopedia Mythica and Myths & Legends, collections of Greek mythology and religion, including source texts, Norse mythology plus translations of the sagas and eddas, the wonder that is GodChecker, these early Jewish and early Christian texts, some catalogs of saints, other sacred texts, an introduction to pantheism, and an excellent catalog of theology resources. And just for fun, practice bibliomancy.