His first imprisonment was at Nottingham, for interrupting divine service; but he had his triumph, the very Sheriff was converted, and compelled by his new-found zeal to go forth into the market-place, and take up the imprisoned preacher's work. His second term soon followed at Derby, on a charge of blasphemy. He believed in the doctrine of perfection, and told those who opposed him that they pleaded for sin. The Derby Magistrates asked him if he was sanctified, and he answered, "Yes." "Then they asked me if I had no sin? I answered 'Christ my Saviour has taken away my sin and in Him there is no sin.' They asked how we knew that Christ did abide in us? I said, 'By His Spirit that he has given us.' They temptingly asked if any of us were Christ? I answered, 'Nay, we were nothing, Christ is all.'" Yet they found him guilty of blasphemy, confounding him with the fanatical, antinomian Ranters. But if he taught perfection, Oh! how he lived! Let those that reject his teaching excel, or at least equal, his living. In Derby, his jailer was converted, to strengthen and comfort him in his sufferings. Whilst in prison his busy pen poured forth many letters of advice to Friends, and "testimonies" against all forms of iniquity, including war and capital punishment.
Before he was 27, Fox had passed through more varied experience than many have in a long life-time. Honour and revilings, converts and imprisonments, love for the gospel's sake and cruel beatings by the mob, nearly ending in death--these had already been his portion. But his work was now bearing much fruit. In one twelve-months, 1650-1, he gained such staunch helpers as Richard Farnsworth, James Nayler, William Dewsbury, Justice Hotham, and Captain Purslow. Soon afterwards the Fells of Swarthmoor were led to Christ by his preaching and became the most devoted of adherents. Soon his followers could be numbered by thousands. It was not the strength of his arguments that gained them; the age was overdone with reasoning. Fox mocked their syllogisms with grim humour. There was a wonderful spiritual power about him. He spoke naturally, with simple, direct earnestness, and overwhelming vehemence, right to the conscience of the hearers. He made people both listen and understand him, and feel the power of the truth in a way which many did not like. He was a wonderful evangelist. What his cultured convert, Isaac Pennington, the Rutherford of Quakerism, said of Friends generally, is applicable to him. They might offend his taste and move him to contempt by their intellectual poverty, but they compelled him to respect their spiritual power and their deep acquaintance with the things of God.