Here is a great quote by A.W. Tozer on the sovereignty of God:
God sovereignly decreed that man should be free to exercise moral choice, and man from the beginning has fulfilled that decree by making his choice between good and evil. When he chooses to do evil, he does not thereby countervail the sovereign will of God but fulfills it, inasmuch as the eternal decree decided not which choice the man should make but that he should be free to make it. If in His absolute freedom God has willed to give man limited freedom, who is there to stay His hand or say, “What doest thou?” Man’s will is free because God is sovereign. A God less than sovereign could not bestow moral freedom upon His creatures. He would be afraid to do so.
A.W. Tozer, The Knowledge of the Holy, chapter 22 “The Sovereignty of God”. (book can be found online here)
I found these illustrations helpful. They explain two different ways of understanding God’s sovereignty and man’s free will. The illustrations and quotes come from the book Foundations of Wesleyan-Arminian Theology, by Mildred Bangs Wynkoop. Illustration “A” represents the Calvinist / Reformed view. With this view, any genuine freedom that man has takes away from God’s sovereignty. Therefore, free will must be rejected in order to protect God. Illustration “B” represents the Wesleyan / Arminian view. With this view, man has genuine (though limited) freedom. Man’s freedom is not a threat to the sovereignty of God.
“When a problem is encountered relative to God’s sovereignty and man’s will, it probably lies in thinking of man’s will as standing over against God’s will, challenging and defying God so as to constitute a threat to God’s will and purpose in His creation. No evangelical Christian would tolerate such an idea. And yet both the full measure of God’s sovereignty and a genuine moral responsibility in man must be accounted for and included in one system without absurd reasoning to explain it.”
“The unsatisfactory concept of man’s freedom in relation to God’s sovereignty could be likened to a set of balancing scales with the weights set against each other. In this view, God’s will is thwarted by man’s will or mans will is thwarted by God’s will. In either case, one of the two is victor, the other vanquished.”
“It seems to be more in keeping with biblical teaching to illustrate the proper relationship by a large circle typifying God’s sovereign will. The small square contained within the circle is the real though limited freedom which God has given to the man He created. In God’s sovereign love He has created morally responsible beings. But man’s freedom is strictly limited by God. God makes the rules. Man is
genuinely free within the limits set by God. God controls nature, the universe, the major lines of history. The natural order is absolute (God is Creator). But there is a vastly different kind of order in back of the natural order, namely the moral order-and the rules are moral rules. God has given man the power of discrimination and the ability to make decisions between alternatives. God’s will and mercy sustain moral freedom in man. In fact, God has made man in such a way the he is under constant necessity of making decisions. He is not free not to make constant moral decisions.”