The role of both theology and dharma is to represent a structure or framework of beliefs for operating within. The dharma, although it does embody some external forces (e.g., karma, reincarnation) is primarily and explicitly about how our minds should operate. In contrast, theology, although it does embody some explicit ideas about how our minds should operate (e.g., love thy neighbor) is primarily and explicitly about outside forces (e.g., God, Jesus, the Devil, angels). So although they seem very different along this dimension, the difference lies in mainly in the emphasis on inner and outer forces. However, in both mystical Christianity and mystical Buddhism, the external forces are understood metaphorically and analogically as describing internal forces, so this difference is more in style than in substance.
In both cases, the mental framework created by these beliefs is a type of virtual computing device that tells us about the relationship between the elements represented in the system, and allows us to use them to think and make choices. However, it is important to note that having part of the framework is of limited use and may even produce a disastrous result (e.g., like driving a car with only three wheels on). This is why it is not a good idea to merely choose bits of different religions that appeal to you and mix them together. Religions need to be understood as a whole. This is one reason why mystics can still be quite dogmatic about their religion. Unfortunately, the other reason is that mystics may attribute their results to the specific representations in their framework, which are specific to their religion. This can lead to the belief that their religion is true (because it delivers the goods) and therefore others must be false, misguided, or confused. It is the contention of this blog, that creating mappings between frameworks, in this case between Christian Theology and Buddhist Dharma, can create deeper insights (or at least equally deep insights), for some people.