After some adventures he reached Dublin, where he found the nonconformist ministers very indifferent to his cause. Proceeding by sea to Scotland, he at once entered on his ministry there. Upon his return to Scotland in 1683 he gave his first sermon, at Darmead, Cambusnethan, choosing passages from the book of Isaiah. Renwick spent the next five years travelling around Scotland ministering. His first sermon (September 1683) was in a meeting at Darmead Moss in the parish of Cambusnethan, Lanarkshire. He soon became noted as a field-preacher, and was proclaimed a rebel by the Scottish privy council. Though his fame spread, his position was variously misconstrued, some charging him with ‘the delirious and detestable blasphemies of Gib,’ the reference being to John Gib, shipmaster of Borrowstounness, Linlithgowshire, who, in April 1681, had started a semi-mystical sect of ‘sweet singers.’ Occasionally Renwick and his followers crept into churches by night and held their meetings. In 1684 efforts were made to apprehend him. In July he was nearly taken by a party of dragoons, but escaped with the loss of his papers. Letters of intercommuning (interdiction) were issued against him on 24 September. His followers hereupon urged the defiant measure of a new declaration, to which Renwick was at first averse. But in October he drew up ‘the Apologetical Declaration’ which, by concerted action, was affixed to a number of market crosses and church doors on 8 November 1684. It claimed the right of dealing with the agents of authority as enemies of God, and ‘murdering beasts of prey.’ Two gentlemen of the king's lifeguards having been slain in an onset upon a field-meeting, the privy council ordered the death penalty for all who refused to disown this declaration on oath. The Scottish parliament, in April 1685, passed a statute making any acknowledgment of the covenant an act of treason. This led to the second Sanquhar declaration, promulgated by Renwick and his followers on 28 May 1685. Renwick refused to join the insurrection of 1685 under Archibald Campbell, ninth earl of Argyll. He was in sympathy with its object, but held aloof from a movement not distinctly put on the basis of the covenant.