Originally a Dominican, he became a Church of Scotland minister with significant extra responsibilities and played an influential part in the Scottish Reformation.

He assisted in compiling the second book of Discipline signed by King James VI, and subsequently censured His Majesty for not dealing justly with his people.

Hewat says: "There must have been something arresting about this young monk, for it was on the recommendation of one so great and influential as Cardinal Pole that he was admitted to a place among the Dominicans in the city of Bologna, where he soon became Master of the Novices.

[17] Spottiswoode relates: "Afterwards when they perceived his diligence and dexterity in businesses, he was employed in all their affairs throughout Italy, and sent on commission to Chios, an isle situated in the Ionic Sea, to redress things that were amiss amongst those of their order".

John Howie in the Scots Worthies tells about the dog: "During his travels abroad he was frequently delivered out of very great dangers, by the kind interposition of a gracious Providence: an instance of which we have while he was in Italy.

"[27] Robert Lippe dismisses these stories saying: "Row adds some additional particulars regarding this imprisonment, such as his being confined in a deep and gloomy vault, where the prisoners had to stand twice a day up to their waists in water by the admission of the tide.

We need not repeat his providential deliverance, escape, and journey to Vienna, and his reception by the Imperial House there — with all the startling attending circumstances — events which read more like a chapter of a thrilling romance than a plain and sober narrative of an actual life.

But long before John Hamilton, able Catholic apologist questioned the story's authenticity in his Facile Tractise (1600) it was alluded to in the satirical verse of Nicol Burne.

[21][32][33] Craig made his way to Vienna, where as a Dominican, he preached before emperor Maximilian II, and soon became a favourite at court but his surrender was demanded by the new pope Pius IV.

John Craig became minister of the Canongate in 1561, making him Mary, Queen of Scots's royal chaplain at Holyrood House in Edinburgh.

[2] The council wrote: "The Council understanding the tedious and heavy labours sustained by their minister, John Knox, in preaching thrice in the week, and twice on the Sunday, ordains unanimously to solicit and persuade Master John Craig, presently minister of the Canongate, to accept upon him the half charge of the preaching in the said Kirk of Edinburgh, for such good deed as they can agree upon.

"[38] The pastoral work was divided in two and both preachers undertook tours to strengthen their cause in other parts of the country: Knox in Nithsdale, Galloway and Kyle in autumn 1562, and Craig in Jedburgh the following year.

[39] They were later able to leave Edinburgh simultaneously for example in 1564 when Craig went back to the Merse churches for a month while Knox engaged in similar work north of the Forth.

Knox was pleased by Craig's outspokeness against the nobility and called him "that worthy servant of God", approving is his public rebuke of courtiers.

The question was debated in August 1575 by a committee appointed for the purpose, in which Craig, with Andrew Melville and James Lawson, was to take the negative side.

It was during his ministry here that he prepared his first or longer Catechism, as in the preface to the work he reminds "the Professovres of Christis Evangell at Newe Abirdene" that it was for their sake chiefly that he "toke paines first to gather this breife summe" and he now (July 1581) in setting it out and making it common to others, recommends the same to them again in special as a token of his goodwill, and a memorial of his doctrine and earnest labours bestowed upon them for the space of six years.

[48] Craig's bold preaching against the nobles who seized the revenues of the church, so that "we can nocht discern the earl from the abbot," provoked the anger of William Maitland of Lethington, and in the memorable conference between that statesman and Knox in 1564 Craig backed his colleague's argument with a telling precedent of a discussion in the university of Bologna, where he had been present in 1554, and heard the thesis maintained "that all rulers, be they superior or inferior, may and ought to be refused or deposed by them by whom they are chosen, empowered, and admitted to their office, as oft as they break their promise made by oath to their subjects, because the prince is no less bound to his subjects than subjects to their princes."

""[43] Craig's name appears with that of Knox in the list of persons privy to Rizzio's death on 9 March 1566, sent by the Earl of Bedford and Randolph to William Cecil.

Mackay says "Proof of actual complicity is wanting, but there can be little doubt that the ministers of the reformed church approved the act after it was done, as Mary did the assassination of her brother James Stewart.

"[43] Kerr says: "Queen Mary, now for the moment all-powerful, issued through her Privy Council a list of those implicated, and it surely bespeaks the innocence of Knox and Craig that they are not mentioned.

"[43][50][51] He got no explanation on any of these points, but a letter from Mary having been shown him denying that she was under restraint, he in the end proclaimed the banns with a protest that "he abhorred and detested the marriage."

Craig submitted a statement about his actions and at the Assembly of 6 July 1569 a resolution was passed absolving him, while Adam Bothwell, the bishop who performed the ceremony, was suspended.

Although he gave offence by this lukewarm attitude, he was chosen by the convention of the kirk at Leith one of the deputies to wait upon the queen's friends in the castle.

[57] The next General Assembly convened during December, 1566, at which a letter, headed by the signature of John Craig, was sent to "their brethren the bishops and pastors of God's Church in England, who profess with us in Scotland, the truth of Jesus Christ."

Kerr comments: "That Craig's name appears at the top of the signatures on the letter, would seem to indicate that at Knox's request, he had assumed the leadership of the Scottish Reformers during the absence of his colleague.

Craig was moreover a vigorous defender of the presbyterial form of church government in opposition to episcopacy, which brought him into conflict with King James.

He drew up the Confession of Faith which was subscribed by James VI, 2 March 1580, and adopted by the nation; was elected Moderator of the General Assembly for the third time, 17 October 1581.

In 1579 Craig, having been appointed one of the king's chaplains, returned to Edinburgh, when he took part in the composition of ‘The Second Book of Discipline’ and ‘The National Covenant’ of 1580.

In October 1581 Craig was sent by the assembly to intimate their approval of the seizure of the king by the Earl of Gowrie in the raid of Ruthven, and boldly rebuked James for his conduct, drawing tears from him as Knox had done from Mary.

[43] When parliament in 1584 passed the Black Acts restoring episcopacy and recognising the royal supremacy, Craig denounced them from the pulpit, and in answer to Arran and the court declared that ‘he would find fault with everything that is repugnant to the word of God.’ A conference at Falkland, where he was summoned by the king, gave rise to a stormy scene between him and Arran, who then ruled the court.