[3] It was chiefly through Gib's influence that the Antiburghers decided, at subsequent meetings, to summon to the bar their Burgher brethren, and to depose and excommunicate them for contumacy.

Gib's action in forming the Antiburgher Synod led, after prolonged litigation, to his exclusion from the building in Bristo Street where his congregation had met.

In 1765 he made his response to the General Assembly of the Church of Scotland, which had stigmatized the Secession as threatening the peace of the country.

From 1753 till within a short period of his death, he preached regularly in Nicolson Street Church, which was constantly filled with an audience of two thousand persons.

While he was attending the undergraduate classes the controversy was going on in the general assembly which led to the formation of the secession church under Ebenezer Erskine and others, and Gib was so impressed with the harsh treatment of the seceders, that he threw in his lot with them.

Gib joined the ‘Associate Presbytery’ founded by Erskine and others in 1735, and was licensed to the West Kirk of Stirling on 5 March 1740.

Gib, however, withdrew with his flock only to the suburbs, and for five Sundays at Dreghorn, near Colinton, three miles from Edinburgh, where the insurgents had a guard, he spoke voice against the "popish pretender" and his cause.

Gib took the side of those who deemed the oath unlawful, and ultimately became the leader of the Antiburgher section of the Secession Church.