Henry Ainsworth (1571–1622 or 1623), leader of the separatist congregation at Amsterdam, and controversialist, was born at Pleasington in 1571. According to Baines and Abram, his father, Lawrence Ainsworth, who married Dorothy, daughter of Thomas Grimshaw, of Clayton, was one of the original governors of Blackburn grammar school, which was founded in 1567. Here, it is conjectured, Henry received the earlier part of his education. He was left an orphan at the age of thirteen. He is said to have proceeded to the university of Cambridge; but his name is not to be found in the 'Athenæ Cantabrigienses.'
Ainsworth was a fine type of the Elizabethan puritan—learned, sincere, earnest, and uncompromising. He attached himself to those who were styled 'Brownists,' who, under the name of 'Independents,' afterwards played so important a part in English history, and who were the ancestors of the 'Congregationalists' and other free churches of the present time. Their essential distinction was the claim that each church or congregation should be a religious republic, regulating its own affairs in entire independence of state control, whether episcopal or presbyterian. A vigorous persecution was directed against these sectaries, and their founder is said eventually to have reverted to the church of England; but some of his followers went into exile rather than recognise the right of the secular power to dictate in such a matter.
Ainsworth entered into the service of a bookseller in Amsterdam as a porter about 1593. He, together with Francis Johnson, founded an independent church, and in 1596 was the author, wholly or in part, of the 'Confession of Faith of the People called Brownists.' The task of organising the new church was not an easy one. Objects of persecution at home and of suspicion in exile, they added to the difficulties of the situation by internal dissension. After many efforts at reconciliation on the part of Ainsworth, he and his friends finally withdrew in December 1610, and the scoffers were soon able to point to the two congregations, whom they styled respectively Franciscan Brownists and Ainsworthian Brownists. Ainsworth was now minister for twelve years. This was a busy time; for, in addition to the work of the pastoral office, he wrote a lengthy series of controversial and exegetical works.
'The Trying out of the Truth, begun and prosequuted in certain letters and passages between John Aynsworth and Henry Aynsworth: the one pleading for, the other against, the present religion of the Church of Rome. This is an interesting memorial of the religious controversy of the Elizabethan age. John Ainsworth, who had abjured Anglicanism, and was imprisoned in London as a recusant, put forth a challenge to a written debate, and invited Henry Ainsworth to notice this cartel. Four letters by the disputants were addressed to each other, and in the published volume Henry Ainsworth ends with a short reply. The discussion extended from 1609 to 1613. It has been said that John and Henry were brothers, but of this there is no evidence. The letters on the whole are remarkable for the earnestness and yet friendly spirit of the disputants in an age when religious controversy was apt to be bitterly personal.
Before his death Ainsworth for a time left Amsterdam and revisited Ireland, but returned to his city of exile, where he died late in 1622 or early in 1623 - a puritans mind.