Missiology helps us to think creatively about theology. It helps us to apply questions about form and meaning to formulations of theology. They are equally biblical, and are complementary, but different models may provide better 'ways in' than others. Then, non-western churches have had to find theological and biblical answers to questions that have not been a part of traditional western concerns, for example, polygamy or ancestor worship or many manifestations of the supernatural. Missiology helps us to think globally about theology and about global theologies.
Postmodernism denies the possibility of metanarratives.
Missiology helps us to discard cultural clutter and bias and to identify more accurately and more defensibly what the metanarrative is. Missiology helps us to think humbly about theology. The purpose of the study of theology is not intellectual titillation or academic oneupmanship, a kind of game of baptized Trivial Pursuit. The purpose of the study of theology is to know God more deeply and to live out more fully our 'image-ness'. Much of the way in which we in the West have done theology, and sadly have exported it, has had Man rather than God enthroned at its center, and has certainly not led to the more worthy worship of God.