Well, first, one might say that knowledge and understanding are vital to ministry because, in order to minister, one must have a sense of the needs one is addressing and how to address them. If we want to care for one another in light of the good news we have in Christ, we need to be both clear about what the good news is (and isn’t) and what sort of freedom follows from it.
Secondly, one might say that knowledge and understanding are vital to theology because theology is talk about God (and all things in relation to God). Given that the scope of this talk is what can be known and understood about God, a theology with neither knowledge nor understanding doesn’t fulfill its end particularly well.