God's Sovereignty vs. Man's Responsibility

If God is in control of our salvation, is there no such thing as human responsibility? How can God hold a man responsible for rejecting the gospel message if that message cannot be received except by a supernatural work of grace in his heart? J I Packer calls this an "antimony...an apparent incompatibility between two apparent truths...an antinomy exists when a pair of principles stand side by side, seemingly irreconcilable, yet both undeniable." Our finite minds want to jettison one or the other of these truths, but the result is a perversion of the gospel.