Robert Haldane, finding no prospect either of active service or immediate promotion, decided to give up the sea. He resigned his commission; and decided to complete the education which had been interrupted three years before, when he went to sea. After a few months in Gosport, sitting under the ministry of Brogue, he then once more became a student at the University of Edinburgh, and after two years he made the grand tour, comprising the principal countries of Europe. After his return he married, in 1786, the seventeen year old Katherine Cochrane Oswald, daughter of George Oswald of Scotstown, and settled down on his father’s beautiful estate of Airthrey, resolving to devote himself to the life and occupations of a country gentleman. For about eight years he threw all his energies, and his taste into improving his estates and landscaping his gardens, and soon he was conspicuous among his peers and people came to him for advice.
Having become a true follower of Christ, Robert Haldane looked for a field of Christian enterprise and soon found it in India. The Baptist mission had just previously been established there, and the account of its proceedings been published; and Haldane, who read the first of its periodical reports, was impatient to enter such a field, and co-operate with the efforts of William Carey and others. He too wanted to become a missionary and devote himself to a life of danger and toil in India. It was a strange plan, but it was not adopted rashly nor unwisely prosecuted. It was on a grand and comprehensive scale, with himself, Dr Innes, minister at Stirling, David Bogue of Gosport, and Greville Ewing, were to go out as missionaries. These were to be accompanied by an efficient staff of catechists, city missionaries, and schoolmasters; and a printing-press, with printers and bookbinders. The whole mission was to be transported to India, and when there, to be supported entirely at the expense of Haldane. To provide a fund for the purpose, he was prepared to sell his rich and beautiful estate of Airthrey. Haldane commented, "Christianity is everything or nothing. If it be true, it warrants and commands every sacrifice to promote its influence. If it be not, then let us lay aside the hypocrisy of professing to believe it."