tsn turning point

Matthew 9:32-34

This happens immediately on the heels of Jesus restoring the sight of the two blind men. There is an interesting parallel between Jesus casting out a demon and the Pharisees accusing him of submitting to demons. This is really the turning point in Jesus' conflict with the Pharisees. They have gone to the next level in their opposition of him and his work. He is no longer just a misguided person but he is now under the influence of Satan and his demons and is on the side of evil. Rather than recognizing the work of the Spirit of God in what Jesus was doing, they attribute it to the work of demons. If this is their conclusion, they have no choice now but to get rid of him. This is why, I believe, Jesus wanted to keep his early miracles as quiet as possible.
I'm not doubting the truth of what Matthew writes but I do wonder if there was a purpose in putting this miracle and this accusation together. Keeping in mind that Matthew's purpose is to prove to his Jewish audience that Jesus was the Messiah, I wonder if he is attempting to show how ridiculous the opposition of the Pharisees was. Jesus points out the absurdity in another passage: Satan is not stupid. He would never start a war against himself. Demons being in opposition to each other does not make sense. Using the idea of C.S. Lewis then, if Jesus was not under the influence of a demon, and therefore a liar, then he was either who he said he was (the Messiah King) or he was insane. I don't know for sure that this is what Matthew had in mind by including this encounter and this accusation so closely together but it definitely supports his thesis.
This encounter raises some questions for me: if this man was living today with all its medical technology, would we have attributed his disability to a demon or to a medical problem? Would medicine have been able to allow him to talk? Are there medical mysteries today that are actually caused by demon oppression? How do we know which ones we should be seeking medical treatment for and which ones we should be exorcising? Have western Christians become so calloused to the spiritual realm that we no longer can discern what is purely physical and what has a spiritual element? Is there anything that is actually purely physical?
The other questions I have are prompted by the Pharisees accusation. In my conservative evangelical comfort zone, I am often suspicious of the spectacular and claims of the supernatural. While I may not directly say that such things are of Satan, by jumping to the conclusion that they are not of God... logically there is only one other conclusion. I recognize that things are not so black and white in this world; everything that humans are involved in is tainted by sin (and conversely, the grace of God). So what I am actually saying is that there is more of sin and evil in these things than there is God. The question, then, is: have I attributed a genuine work of God's Spirit to the work of Satan and his demons? I must be very careful in my judgements! I don't want to be in the same boat as the Pharisees.