There are a ton of applications in the passage, and we explored many of them, but there was that one statement that kind of hung in the air: "God sent a plague." Throughout the Old Testament, the bible often refers to illnesses and disease and death having their origin in God...while in the New Testament, Jesus clearly ascribes them to the work of the devil. Which are we to believe? God didn't change. But perhaps the perspective of people did. In the OT, it was common to attribute to God as the prime "cause" behind everything that occurred. Little mention was given to intermediary causes, such as "consequential action" (reaping what you sow). When you did wrong, and disaster struck, it was God who was punishing you. This eventually led to a questioning by these very same bible writers (David, Solomon and others) about why the wicked often prosper and don't seem to get punished.
When Jesus arrives upon the scene, we get a picture of the exact nature of God. In fact, in Jesus we see the exact representation of the Father. (If you have seen me, you have seen the Father). Jesus is perfect theology. When Jesus said "I only do what I see the Father doing" He was affirming that He did and said nothing that was not consistent with His Father's nature and will. So, when He healed people from sickness, being lame, blind, etc. and said, "this person was held captive for #years by the devil" He was emphatically saying that "My Father isn't responsible for this sickness" all while saying, "My Father will get glory from this."
As a result of having the New Testament, Jesus, and the Old Testament, we can fully see the nature of our God, a loving Father, whose patience is nearly unlimited, whose grace is amazing, whose love is unfathomable, and yet, who is perfectly holy, just and sovereign. Some may think it is an affront to the sovereignty of God to say that God doesn't send disease (because God has the final word in whatever happens to us. By and large, God has "delegated" His sovereignty to other instruments, such as angelic beings (Satan), men and even the constructs of nature, leaving a huge swath of free will and choice in the wake of our lives that we live here.
Imagine that the church has the power to heal in Jesus name, to move mountains in Jesus name, to feed the sick, raise the dead, cast out demons...and does not use that power and authority it has been delegated. We shouldn't have to imagine. It is there in red letters in the words of Jesus.