Born at Haddington (East of Edinburgh), Knox was educated at St Andrews and ordained a priest in 1536. Influenced by the teaching and martyrdom of George Wishart, Knox was called as a preacher in the turmoil at St Andrews in Easter 1547 following the murder of Cardinal Beaton. Knox joined those responsible who were occupying St Andrews castle. Help promised from England never came, and Knox and others were captured by the French navy sent to restore Catholic order in Scotland.
For 19 months Knox was a slave rowing in French galleys before he was released. He pastored in Berwick and Newcastle and assisted in the Edwardian phase of the English Reformation from 1549 to 1553. He returned to Europe following the death of Edward, as one of the Marian exiles. He was influenced by Calvin and Bullinger, consolidated his theological and liturgical views, and pastored English congregations in Frankfurt and Geneva. In 1555 he secretly returned to Berwick to marry Marjory Bowes and visit underground churches in Scotland.
Knox's conflicts in Frankfurt over what constituted acceptable worship demonstrated his conviction that the Catholic mass amounted to idolatry, and that Protestant liturgies had to scrupulously avoid all associations with the old faith. An important text was Deuteronomy 12:32. His liturgy from Frankfurt and Geneva still shapes Presbyterian worship.
In 1558 he wrote his First blast of the trumpet against the monstrous regiment of women, perhaps neither foreseeing nor much caring that this might have implications beyond the evils of the reign of Mary Tudor. It certainly helped ensure that he had little ecclesiastical future in the England of Elizabeth I. More importantly he and Calvin had come to allow for an ordered form of civil disobedience by which tyrants might be legitimately overthrown by legitimate subordinate bodies. Views which became a sometimes but not always forgotten element in Reformed Christianity.
In May 1559 Knox returned to Scotland, preaching against idolatry, sparking a riot in Perth and instances of armed confrontation. He supported the "Lords of the Congregation" who with English help gained a political base for Scotland to become Protestant - despite a Catholic queen. He became minister of St Giles until his death and in 1560 helped prepare the Scots Confession and the First Book of Discipline. He was a vocal critic of Mary Queen of Scots who had returned in 1561 and after her abdication preached at the coronation of her son, James VI of Scotland, later to be James I of England.
Knox's style needs to be judged against the times. It might be argued that he was moderate compared with some other voices, but whether his attitude towards the mass and more Anglican forms of worship is justified by the reasons he gave or not, he succeeded in crystallising the difference between the old way and the new, and provided theological principles and an example of a stubborn resistance to compromise which continues to challenge. Some feel that his place in the story of the Scottish Reformation is too much dependent on his own writings, particularly his History of the Reformation, yet his influence is real enough. The vision of a school in every parish is attributed to him in a way which ensures that if Reformed Christianity may or may not still be the dominant religion of Scotland, then valuing education as a means to salvation certainly is.
"Knox was neither a systematic theologian nor an original thinker but his ideas have had a long-term influence upon Scottish thought. He had a hand in the compilation of all the key works which helped to establish the new church in 1560: the Scots Confession, the First Book of Discipline, the Book of Common Order and the Geneva translation of the Bible, but his colleagues should be given more credit than they have received hitherto. Knox was not a good organizer and was too dogmatic to be a successful politician, which limited his influence outside times of crisis. His prophetic voice and inspiring sermons were extremely important, particularly in 1559-60, but the consolidation of the church after 1560 was largely the work of others." Jane Dawson in Michael Lynch, ed., The Oxford Companion to Scottish History, 2001, 371.