From 1973 to 1987, John Zizioulas taught Systematic Theology at the University of Glasgow, which offered him more attractive terms, both financially and positionally, at first as Senior Lecturer, then as Reader, and after one year as Professor of Systematic Theology, a position which was given to him for reasons of international recognition of personal scientific contribution.

During his approximately fourteen years of academic teaching at the University of Glasgow, he covered all aspects of Systematic Theology with his lectures, the seminars he directed, and the supervision of the preparation of doctoral theses. Specifically, he taught:

a) Introduction to Systematic Theology, with particular reference to the interpretation of dogma and its philosophical ramifications.
b) Analysis and interpretation of the Symbol of faith.
c) The doctrine of God and the Holy Trinity.
d) Christology.
e) Pneumology.
f) Christian anthropology.
g) Ecclesiology.
h) Eschatology.

He also led seminars on the examination of the patristic sources of systematic theology, with special reference to the Church Fathers Justin, Athanasius, Basil, Cyril of Jerusalem, and Augustine.

A unique feature of his entire teaching was the comparison of the Western (Protestant and Roman Catholic) with the Orthodox tradition and theology, and the promotion of Orthodoxy in ​​the West. His contribution to the promotion of the Orthodox tradition and the influence he exerted on his students, as well as his total contribution to the University, were greatly appreciated by the authorities of the University, as shown not only by the highly honorable positions in which they placed him, but also from what was written on various occasions by them.

In 1987 he resigned from his position at the University of Glasgow, making use of the Voluntary Retirement Act (which applied to the whole of Great Britain that year), due to his transfer and appointment as its Professor of Dogmatics at the University of Thessaloniki, but also of his election and ordination as Metropolitan of the Ecumenical Patriarchate.