In Meditation 6 (and the corresponding question that since God is good, knowledge is possible), the separation of Mind and Body and the theory that God is no deceiver seem to be faulty.
Just as in the "What is Truth" paper, I disagree that just because the Yanomamos believe seizures are caused by evil spirits and our doctors believe seizures are caused by epilepsy, neither one of those are the truth. One must break down the component parts that trigger a seizure, not merely label it "epilepsy." There are neurons and brain lesions and synapses, etc., all which culminate in a seizure that we call epilepsy. There is absolute truth, I believe, which is the underlying substance of epilepsy, and body, and mind, but to get to it, one has to disassemble all the particles.
Descartes' perception is that mind and body are separate and different, but if we were to reduce each to the stuff of God, we might discover that it's all the same.
So is God deceiving us, or giving us the tools to determine our own realities out of a common absolute?