At the age of 22, the young William Penn distanced himself from his family's distinguished history of Anglicanism and became a Quaker. Thereafter, Penn's religious views effectively exiled him from English society. Consequently, he was arrested several times.
In one of these cases, Penn pleaded for his right to see a copy of the charges laid against him and the laws he had supposedly broken, but the judge, the Lord Mayor of London, refused — even though this right was guaranteed by the law. Eventually, he was let out.
The persecution of Quakers became so fierce that Penn decided that it would be better to try to found a new, free, Quaker settlement in North America. In 1677, Penn's chance came, as a group of prominent Quakers, among them Penn, received the colonial province of West New Jersey. He established one of the most civilly liberal colonies.
However, lets go back to his time in jail. He spent two years in confinement and wrote extensively on religious freedom – namely "The Great Case of Liberty of Conscience."
In this great essay, Penn wrote that "Liberty of Conscience" is not merely a internal conscience of mind, but a right to exercise your religion freely.
After working in America, he returned to England to work for the persecuted Quakers. In 1686, through his influence, all persons imprisoned on account of their religious beliefs were released.
Here is an excerpt from Penn's essay:
"THE great case of Liberty of Conscience, so often debated and defended (however dissatisfactorily to such as have so little conscience as to persecute for it) is once more brought to public view, by a late Act against Dissenters, and Bill, or an additional one, that we all hoped the wisdom of our rulers had long since laid aside, as what was fitter to be passed into an act of perpetual oblivion. The kingdoms are alarmed at this procedure, and thousands greatly at a stand, wondering what should be the meaning of such hasty resolutions, that seem as fatal as they were unexpected. Some ask what wrong they have done? Others, what peace they have broken? And all, what plots they have formed to prejudice the present government, or occasions given to hatch new jealousies of them and their proceedings? being not conscious to themselves of guilt in any such respect.
"For mine own part, I publicly confess myself to be a very hearty Dissenter from the established worship of these nations, as believing Protestants to have much degenerated from their first principles, and as owning the poor despised Quakers, in life and doctrine, to have espoused the cause of God, and to be the undoubted followers of Jesus Christ, in his most holy strait, and narrow way that leads to the eternal rest. In all which I know no treason, nor any principle that would urge me to a thought injurious to the civil peace. If any be defective in this particular, it is equal both individuals and whole societies should answer for their own defaults; but we are clear."