On 14 and 16 July he was tried by court-martial, but nothing was proved against him; he was never a United Irishman. However, he was detained in durance, and his third daughter, Margaret, a girl of sixteen, voluntarily shared his imprisonment. On his release, after a long confinement, he could obtain no redress. In religion, as in politics, he was a pronounced liberal, though no controversialist. His manuscript sermons are unmistakably Arian, and in the original draft of his "Remarks" he says, "Suppose now any legislator should so far forget common sense as to decree three one, and one three, &c." He was fond of quoting the Greek Testament in his sermons, and (marvellous to say) his draft of a petition to parliament from his presbytery contains two citations from Theodoret in the original. For an incident of his pastoral experience, turning on the difficulties of the then Irish marriage law, can be found in the autobiography of Catherine Cappe. Montgomery assigns to him "a singularly vigorous mind, a cultivated taste, a ready wit, a fluent elocution, a firm purpose, an unsullied character, and a most courteous demeanour." Barber died 5 September 1811, in his seventy-fourth year. In 1771 Barber married Elizabeth, eldest daughter of the Rev. Andrew Kennedy, of Mourne, and had seven children, but no son survived him. His daughter Margaret, (12 August 1782 – 21 May 1875), married John Galt Smith, of Belfast. George Kennedy Smith, his son, was left Barber's portrait and manuscripts. Barber wrote: