Why such a different form of worship?
Some history...

The Wikipedia entry for the Society of Friends provides some detail and might be a good starting point for deep learning about the history of the movement. But briefly...

To understand why Quaker worship services are so different from those of mainline churches, we must go back England to the middle of the 17th century. It was a time of enormous religious hunger. Religion was the topic of the day.

Most people believed that a right relationship with God and correct beliefs about God were the most important thing in life. There were discussions everywhere, not always civilized, and those who thought differently from the mainstream beliefs of the Church of England, were often ridiculed and sometimes attacked.

17th Century Seekers

One group of “seekers” turned away from all external forms of religion. They would come together in silence on the basis of one central thought: “Christ has come to teach his people himself.” Every person has a spark of God in their soul and therefore the potential to hear God’s message. It wasn’t necessary to have studied theology. In worship there would be no preaching based on previously written words, but only on the basis of what God’s Spirit would make clear at that moment in the silence of worship.

The people who would meet together in this way on Sundays called themselves, “Children of the Light.” Being obedient to the God-given Light was the most important thing in their lives. There was a danger, of course, that someone might hold their own thoughts or wishes to be those from God. But it was understood that the group, the Meeting, was prepared to know the difference between what was from God and what was merely human. The Bible was a big help in this regard. God would not contradict himself.

Quaker Insights

Their silent meetings produced the following insights, insights that are still followed by Quakers today:
  1. A life inspired by God is an honest life. This means that one does not swear an oath, since oaths are founded on the idea that one sometimes speaks the truth and sometimes not. Quakers, while not swearing an oath, hold themselves accountable for their words at all times. Also, if a Quaker owned a store, it meant that the prices were the same for everyone, no bartering, no favors. One could send a child to such a store and know that she would be treated fairly and the same as any adult. At that time this was very unusual.
  2. God’s Spirit is accessible to both men and women. They knew this based on their own experience and found it affirmed by the prophet Joel, who wrote: “I will pour out my Spirit on all that lives; your sons and your daughters shall prophesy.” From the beginning, women have played an important role, and in South America, Quakers are one of the very few churches where women hold positions of leadership.
  3. Quakers are pacifists. To kill a person is to extinguish the spark of God in this world. Quakers don’t participate in wars, but help victims of both sides of a conflict. They study issues of war and peace and make serious efforts to facilitate reconciliation between opposing parties. In the 1990s, the Quakers in Burundi and Kenya were the first to offer their churches and meeting houses as places where the Hutus and Tutsis could come together to work through the horrors and slaughter of their war, and hopefully learn again to live together in peace.

Modern Quakers

The Quaker movement from the 17th century began to see itself as a church and not just as a reform movement. It was a woman, Margaret Fell, who had the most important role in organizing this church, into what is called “The Religious Society of Friends.”

Today, Quakerism has both a mystical and a practical foundation. Friends take seriously the words of Jesus about being the “salt and light of the world.” They support each other in discovering one’s personal calling.