"God, in his ordinary providence, maketh use of means, yet is free to work without, above, and against them, at his pleasure."
-- Westminster Confession of Faith, Chapter 5.
This statement succinctly formulates the status of creation in Christian theology: ordinarily, God operates into the creation through means, or second causes (that is, the ordinary regularities that we sometimes call physical laws). However, God in no way is restricted in using such means to act into the creation. In other words, miracles of direct divine intervention are always possible; the world is an open system, not a closed system of causes and effects. It is open from above.
We too are among the means God uses to do his will. We, as God's creatures, have an opportunity to participate in God's providence in the world, in the struggle against evil.