What is a Miracle?
Churches of Christ often teach that miracles don't happen today. There's certainly a case to be made for that; however, too many Christians extrapolate from this conviction that God doesn't act in the modern world. They argue that if God doesn't give men miraculous gifts today then everything must be explained through providential action bound by natural laws (it should be noted that the concept of natural law operating without God's sustaining power is a post-Enlightenment construct).
It's not difficult to see how restricting God to providence handicaps his ability to work. If the manipulation of natural material substances by a supernatural spiritual God constitutes a miracle, which can no longer happen, then God is basically incapable of doing anything.
For example, if we pray for God to "guide the hands" of a surgeon operating on a loved one then we're expecting God to do something miraculous because on some level he would have to manipulate matter or chemicals or electrical impulses inside the doctor's body in order to "guide his hands." If we pray for God to help us safely reach our destination while traveling we must expect that on some level God will manipulate our minds or the people or material around us to ensure that we don't die or get seriously injured or lost. In fact, most of the things we pray for can only be fulfilled via some intrusion of a supernatural force into the natural world on some level (even if its microscopic and imperceptible).
The Bible doesn't define "miracle" as an act of God that defies natural law. That definition is man-made. Miracles in the Bible are signs that confirm God's will or help his people in some way (among other things). Most biblical miracles could be explained in providential language. We could say that when Jesus healed a blind man it was really God shifting genes, cells, and atomic particles in some way that led to the man's sight being recovered. When Jesus walked on water we could say that God condensed water molecules under his feet until they were solid enough to prevent his sinking. We could deconstruct every miracle in this way until there was technically nothing supernatural about any of the miracles we find in the Bible. However, to do this would be to miss the point.
The danger in saying "miracles don't happen today" is that we don't really know what miracles are, and we end up inadvertently becoming deists. I've personally encountered numerous Church of Christ members who claim to believe prayer works but then deny every mechanism where by God could answer prayer. We need to define what we mean by "miracle" before we go around denying God's ability to work.