Historians are often reluctant to identify a “center” to a theologian’s thought, for fear of reductionism. For example, Carl Trueman, in his excellent book The Claims of Truth: John Owen’s Trinitarian Theology, writes:
. . . the intellectual content of Owen’s thought defies simplistic reduction to one or two key themes. His use of the various strands of the Western tradition, the need to develop new ways of expressing and defending Reformed theology in the light of novel heresies and attacks, and the sheer breadth of his own reading all suggest that we are dealing with a thinker whose thought can be reduced to a few simple ‘big ideas’ only at the cost of losing much of the subtlety of what he has to say, and indeed transforming his theology into a caricature which he himself would not have recognized. (43)
The warning is well taken, but I still find it hard to argue with Richard Daniels, who writes in The Christology of John Owen:
. . . there is one motif so important to John Owen, so often and so broadly cited by him, that the writer would go so far as to call it the focal point of Owen’s theology. . . . namely, the doctrine that in the gospel we behold, by the Christ-given Holy Spirit, the glory of God “in the face of Christ” and are thereby changed into his image. . . . (92)
. . . the knowledge of Christ was the all-surpassing object of Owen’s desires, the center of his doctrinal system, and the end, means, and indispensable prerequisite for Christian theology. (516)
The answer, ultimately, is connected to Owen’s vocation as a pastor-theologian who loved and cared for his flock.
Steve Griffiths, in Redeem the Time:
To date, no one has yet managed to reveal Owen the man. In an attempt to meet this challenge, new questions have had to be asked of Owen and a new premise has had to be sought in approaching his writings, namely: what was of fundamental importance to Owen and what was his primary motivation in ministry?
The answer is blindingly simple. Owen was a pastor. Of fundamental importance to him was the spiritual growth of those amongst whom he ministered. His primary motivation was the growth in holiness of his flock. Everything else stems from that truth. (13)
Sinclair Ferguson, in John Owen on the Christian Life:
My own reading of Owen has convinced me that everything he wrote for his contemporaries had a practical and pastoral aim in view—the promotion of true Christian living. (xi)
And David Clarkson said in his funeral sermon for Owen:
I need not tell you of this who knew him, that it was his great Design to promote Holiness in the Life and Exercise of it among you.
What a legacy to leave: after 24 volumes of writings, 300-400 years later, people still summarize his life and theology by saying it was to promote living life for the glory of God in the face of Jesus Christ.