To say that the grace of regeneration is irresistible is simply to say that this grace, which is so vital to our salvation, is sovereign. This grace is dispensed sovereignly and freely by God. It is truly grace, with no mixture of human merit of any kind. By this grace the captives are set free and the dead in sin are raised to new life. This is the manifest work of the tender mercy of God, who stoops to rescue his children from sin and death and who, as he did in the initial work of creation, takes pieces of clay that are spiritually lifeless and breathes into them the breath that quickens them.
Sproul, R.C.; Grace Unknown: The Heart of Reformed Theology; Baker Books; Grand Rapids, MI; copyright 1997; p. 196