All dogmatic formulations are rational, and every dogmatic procedure is rational to the degree that in it use is made of general concepts, i.e., of the human ratio. It can be called rationalistic, however, only when we can show that the use is not controlled by the question of dogma, i.e., by subordination to Scripture, but by something else, most probably by the principles of some philosophy. If it is clearly understood that dogmatics generally and necessarily involves rational formulation, a rational formulation which is, of course, related to a completed proof and which takes account of Scripture, then no objection can be taken to logical and grammatical formulae as such, for we fail to see why these should be especially suspect more than certain legal formulae. The only thing is that we must ask whether in a given case they are appropriate to the matter or not, which means, concretely, whether it is an arbitrary anticipation, simplification, or even complication . . . [of] what Holy Scripture tells us. [Karl Barth, Church Dogmatics 1.1, 296-7] [full post by Travis can be found here]
This is an important qualification brought to mind by Barth (thanks to Travis). I don't think this is probably a problem people often associate with me---that is being irrational (although my wife often thinks so ;-)---but I don't traffic in the kind of theological discourse (analytic theology) that is normally associated with being rational or rationalist; instead I follow a kind of theological method that is known as dialectic, where paradox is often celebrated as a virtue instead of a vice in theological thinking. And yet, it should be clear that I am not interested in irrational or non-realist types of theological thinking; instead I want to be very rational only because to be rational is to participate in a God of order and thoughtfulness. But that said, there is a difference between being rational (thoughtful and coherent in thought) V. rationalistic. Rationalism, as a thought-system, takes shape by grounding its method in philosophical abstraction instead of Christological particularity and concreteness. It is as Barth underscores above, a system of thought that does not situate itself, primarily within a properly oriented dogmatic schema; which is 'in Christ', in principle.
So I am really only interested in doing theology from a rational point of view, but not a rationalistic one. To me, this means, that everything becomes 'Christ-conditioned'; meaning that hermeneutics, a doctrine of God, a doctrine of Scripture, a doctrine of salvation, a doctrine of eschatology will all take shape with Christ as front-and-center.
Everyone say thank you to Travis for providing this quote for us ;-).