After discerning his avocation towards priesthood, G.S Luke moved to the United Theological College, Bangalore where he studied from 1945 to 1948[4] for the graduate course leading to Bachelor of Divinity awarded by the Senate of Serampore College (University), India's first[5] {a University under Section 2 (f) of the University Grants Commission Act, 1956}[6] with degree-granting authority validated by a Danish Charter and ratified by the Government of West Bengal.
In 1979, Bishop P. Solomon retired on attaining superannuation and the bishopric remained sede vacante.
The Church of South India Synod appointed G. S. Luke whose consecration took place at the CSI-Epiphany Cathedral, Dornakal by N. D. Ananda Rao Samuel and Solomon Doraiswamy.
[8] In 1983, Luke attended a national colloquium in Madras on Christian perspectives on contemporary Indian issues[9] in which K. M. Mammen Mappillai also happened to take part.
On his bishopric, Luke became a member of the Board of Governors of the Andhra Christian Theological College, Hyderabad in which the Diocese of Dornakal also has a stake.