Quakerism came out of the wreckage of the English civil war, when censorship collapsed and every kind of religious claim could be made in public for the first time.
George Fox, a weaver's son, began preaching around 1647 that no amount of steeple-house religion, university learning or ordained ministry could supply what he called that of God in every person, an immediate inward light available to anyone, requiring no priest and no sacrament. The name Quaker was a magistrate's sarcasm about trembling before the Lord, and Friends adopted it.
The claim had consequences the movement did not treat as optional. If the light is in everyone, then social distinctions are false, so early Friends refused hat honour, refused the deferential you for social superiors and addressed everyone as thee, and refused oaths on the ground that a truthful person needs no second standard of truth. Refusing oaths meant that Friends could not testify, hold office, matriculate or defend themselves in court, and the Quaker Act of 1662 and the Conventicle Acts made their meetings illegal. Thousands were imprisoned and hundreds died in gaol. Four were hanged in Boston.
The peace testimony, issued to Charles II in 1660, denied all outward wars and fightings with any weapon for any end, and it has held. Friends supplied the first sustained arguments for conscientious objection in the English-speaking world and paid for them in every subsequent war.
Two abolition points belong here without embellishment. Friends were early and disproportionate in the anti-slavery movement, and the Germantown protest of 1688 is among the first American documents against it. Friends also owned slaves, and it took the Society roughly a century of internal argument to require members to give them up.