When Dr. Cairns came to Edinburgh from Berwick, it was only to a limited extent that he allowed himself to take part in public work outside that which came to him as a minister and Professor of Theology. There were, however, two public questions which interested him deeply, and the solution of which he did what he could by speech and influence to further. One of these was the question of Temperance. During the first twenty years of his ministry he had not felt called upon to take up any strong position on this question, although personally he had always been one of the most abstemious of men. But about the year 1864 he had, without taking any pledge or enrolling himself on the books of any society, given up the use of alcohol. He had done so largely as an experiment—to see whether his influence would thereby be strengthened with those in his own congregation and beyond it whom he wished to reclaim from intemperance.
When he became a professor he was invited to succeed Dr. Lindsay as President of the Students' Total Abstinence Society, and, as no absolute pledge was exacted from the members, he willingly agreed to do so. From this time his influence was more and more definitely enlisted on behalf of Total Abstinence, and in 1874 he took a further step. In trying to save from intemperance a friend in Berwick who was not a member of his own congregation, he urged him to join the Good Templars, at that time the only available society of total abstainers in the town. In order to strengthen his friend's hands, he agreed to join along with him. This step happily proved to be successful as regarded its original purpose, and Dr. Cairns remained a Good Templar during the rest of his life.
While there were some things about the Order that did not appeal to him, such as the ritual, the "regalia," and the various grades of membership and of office, with their mysterious initials, he looked upon these things as non-essentials, and was in hearty sympathy with its general principles and work. But, although he was often urged to do so, he never would accept office nor advance beyond the initiatory stage of membership represented by the simple white "bib" of infancy. On coming to Edinburgh, he looked about for a Lodge to connect himself with, and ultimately chose one of the smallest and most obscure in the city. The members consisted chiefly of men and women who had to work so late that the hour of meeting could not be fixed earlier than 9 p.m. He was present at these meetings as often as he could, and only lamented that he could not attend more frequently.
While fully recognising the right of others to come to a different conclusion from his own, and while uniformly basing his total abstinence on the ground of Christian expediency and not on that of absolute Divine law, his view of it as a Christian duty grew clearer every year. And he carried his principles out rigidly wherever he went. He perplexed German waiters by his elaborate explanations as to why he drank no beer; and once, as he came down the Rhine, he had a characteristically sanguine vision of the time when the vineyards on its banks would only be used for the production of raisins. At the same time his interest in Temperance work, alike in its religious, social, and political aspects, was always becoming keener. He was frequently to be found on Temperance platforms, and was in constant request for the preaching of Temperance sermons. Some of his speeches and sermons on the question have been reprinted and widely read, and one New Year's tract which he wrote has had a circulation of one hundred and eighty thousand.
The other question in which he took a special interest was that of Disestablishment. To those who adopted the "short and easy method" of accounting for the Disestablishment movement in Scotland by saying that it was all due to jealousy and spite on the part of its promoters, his adhesion to that movement presented a serious difficulty. For no one could accuse him of jealousy or spite. Hence it was a favourite expedient to represent him as the tool of more designing men—as one whose simplicity had been imposed upon, and who had been thrust forward against his better judgment to do work in which he had no heart. This theory is not only entirely groundless, but entirely unnecessary; because the action which he took on this question can readily be explained by a reference to convictions he had held all his life, and to circumstances which seemed to him to call for their assertion.
He had been a Voluntary ever since he had begun to think on such questions. His father, in the days of his boyhood, had subscribed, along with a neighbour, for the Voluntary Church Magazine, and the subject had often been discussed in the cottage at Dunglass. It will be remembered that during his first session at the University he was an eager disputant with his classmates on the Voluntary side, and that towards the close of his course, after a memorable debate in the Diagnostic Society, he secured a victory for the policy of severing the connection between Church and State. These views he had never abandoned, and in a lecture on Disestablishment delivered in Edinburgh in 1872 he re-stated them. While admitting, as the United Presbyterian Synod had done in adopting the "Articles of Agreement," that the State ought to frame its policy on Christian lines, he denied that it was its duty or within its competence to establish and endow the Church. This is, to quote his own words, "an overstraining of its province,—a forgetfulness that its great work is civil and not spiritual,—and an encroachment without necessity or call, and indeed, as I believe, in the face of direct Divine arrangements, on the work of the Christian Church."
These, then, being his views, what led him to seek to make them operative by taking part in a Disestablishment campaign? Two things especially. One of these was the activity at that time of a Broad Church party within the Established Church. He maintained that this was no mere domestic concern of that Church, and claimed the right as a citizen to deal with it. In a national institution views were held and taught of which he could not approve, and which he considered compromised him as a member of the nation. He felt he must protest, and he protested thus.
The other ground of his action was the conviction, which recent events had very much strengthened, that the continued existence of an Established Church was the great obstacle to Presbyterian Union in Scotland. It is true that there was nothing in the nature of things to prevent the Free and United Presbyterian Churches coming together in presence of an Established Church. As a matter of fact, they have done so since Dr. Cairns's death, though not without secessions, collective and individual. But experience had shown that it was the existence of an Established Church, towards which the Anti-Union party had turned longing eyes, which was the determining factor in the wrecking of the Union negotiations. Besides, Dr. Cairns looked forward to a wider Union than one merely between the Free and United Presbyterian Churches, and he was convinced that only on the basis of Disestablishment could such a Union take place. To the argument that, if the Church of Scotland were to be disestablished, its members would be so embittered against those who had brought this about that they would decline to unite with them, he was content to reply that that might safely be left to the healing power of time. The petulant threat of some, that in the event of Disestablishment they would abandon Presbyterianism, he absolutely declined to notice.
The Disestablishment movement had been begun before Dr. Cairns left Berwick, and he supported it with voice and pen till the close of his life. He did so, it need not be said, without bitterness, endeavouring to make it clear that his quarrel was with the adjective and not with the substantive—with the "Established" and not with the "Church," and under the strong conviction that he was engaged "in a great Christian enterprise."