The intersection of philosophy and theology is termed natural theology. As such, natural theology is a branch of both philosophy and theology, though Wikipedia characterizes it only as a branch of theology, perhaps reflecting its predominantly secular collective orientation.
In the subject of relational theology, it is necessary to address fundamental issues of both philosophy and natural theology before beginning to address issues of revelation, such as what may be learned from revelation.
It is possible, for example, to address fundamental questions of free will and morality without directly addressing transcendence from material reality. Having pondered this question for several decades, however, it is my firm belief that the typical hypotheses of material reality do not lend themselves to an interesting or important formulation of moral necessity or moral responsibility. Immanuel Kant's effort to construct a secular notion of moral value in his categorical imperative is a valiant one, but ultimately subject to trivializing paradoxes in a purely material context.
It is possible to address questions about the origin of the universe from a scientific perspective if one is only concerned about physical causality, but the fundamental question of why there is such a thing as causality remains elusive in pure philosophy, as David Hume discovered, post-modern efforts to trivialize the question using quantum theory arguments notwithstanding.
When impatience with the trivial consequences of logical and scientific positivism finally takes hold of a thinking human being, the need for some kind of transcendence hypothesis becomes painfully evident. All of the world's great religious figures have confronted this problem, with varying degrees of success and assistance. Without an appeal to something beyond material reality, there is no possibility of a satisfactory discernment of meaning in, not just human existence, but in existence, itself. One could say that the question of the meaning and importance of existence, especially human existence, has been the one question that has universally preoccupied all philosophers and theologians (or, more generally, transcendence metaphysicians) in human history. This is what largely accounts for the loss of interest in metaphysics and meaning in modern secular institutions. In its place, individuals are consigned to the purely subjective private context, in the modern existentialist pose, when considering meaning. Unfortunately, when meaning becomes a purely private and subjective affair, so does morality, and the chief existential dilemma of post-modern civilization can be traced to this unfortunate, though obviously necessary, limitation of the purely secular perspective.
The concern of relational theology (or of relational transcendence metaphysics) can be characterized as the analysis and description of the important relationships between human beings in particular and human existence in general and whatever it is that is hypothesized as beyond material reality. It is principally in the elucidation of these relationships that it is possible to construct meaning.
At this introductory level, we need not concern ourselves with a rigorous definition of material reality beyond noting that some appeal to a via negativa becomes necessary when situating the discussion of the merely material within any larger context. This is an inevitable consequence of the relational perspective in addressing questions of metaphysics.