Julian Hartt’s Four-sided Theological Analysis

I have found myself over and over returning to this quote:

Hartt knew that the Christian church could not make gospel sense of its own life apart from the culture in which it was immersed. In this regard he reversed his senior Yale colleague H. Richard Niebuhr. For Hartt, Niebuhr's pure dichotomy ("Christ" over against "culture") never existed. In its stead Hartt developed a four-sided theological analysis:church, world, kingdom, and gospel were each to be distinguished yet always to be related to one another, and the task was to recognize their mutual involvement, sorting out the contemporary living gospel whose "preachability" would shape the church and inform the world for the sake of the kingdom of God.

James William McClendon Jr.: Systematic Theology, Vol. 3: Witness (Nashville: Abingdon, 42). Italics added. Here McClendon describes Julian Hartt's quadratic understanding of missiology. In summary, a precise theological analysis will need to refer to church, world, kingdom and gospel.