All theology is systemic. Theology is about how God relates with all of creation. It's not just about "me," focused on the situations I experience and might experience. It's about all the experiences, good and bad, that affect others but not me -- about the wealth and relationships I might not have, about the loss I might not experience. Theology is about how God views and works in systems -- economies, politics, religions, empires -- and not just in relation to "us."
But can theology be systematic? Theology is not an engineering problem, one in which all the inputs and outputs can be known and measured, and the processes clearly explained, allowing for predictive laws to address any set of circumstances. Or it might be. All that we know is that the experimental data is not all in yet.
Theology encompasses revelation and mystery. It is informed by what God has revealed of God's self and by the historic record, and is open to the ways God's Spirit chooses to move in the midst of our ever changing reality. If we are engaged in a relationship with God, what we learn about God and ourselves as well as the world and community we live in will be reflected in a relational theology.