“For God, unless men be themselves wanting to His grace, as he has begun the good work, so will he perfect it, working in them to will and to accomplish.” (Council of Trent)
God is all-knowing, and so He knows who ultimately will be saved and who will be lost. God is all-powerful, so it might seem as if His grace alone, or His decision alone, determines who is saved and who is condemned. But God is Love, and love never compels anyone to do good, nor to do evil. Love always respects free will. For without freedom, love is not love. And God is humble, so much so that His all-powerful grace bends itself to our lowly free will, allowing those who choose to do so, to be lost to mortal sin and to eternal condemnation in Hell. But God is also merciful, and so He provides a path to salvation for all human persons without exception. No one is predestined to Heaven in such a manner that they are unable to freely choose Hell (by choosing to sin gravely and by choosing not to repent). No one is in effect predestined to Hell by being passed over for, or passively omitted from, predestination to Heaven.
No one is destined to sin gravely, nor destined to be condemned to Hell, except in the sense that God foresees their entirely free choice to sin gravely and to refuse to repent, despite His many graces. For even the most sinful human persons on earth have the benefit of the providence and grace of God, seeking their salvation and offering even these two wicked persons the possibility of Heaven, if only they were willing. But free will is not an illusion, nor is it a trivial part of salvation. Every sinner has all the graces needed to be saved, without any exception or limitation whatsoever, and yet some freely choose — and grace humbly allows them to freely choose — to sin gravely and to refuse to repent.
Grace has no meaning apart from free will; and free will is not truly free without grace. And so the grace of final perseverance (the grace to continue in a state of grace until death) is not merely a gift given to some and withheld from others. Instead, the grace of final perseverance is partly a gift of grace and partly an act of free will. All human persons are offered the gift of final perseverance by God, but some persons freely refuse to accept that gift. How can a mere weak and mortal human person reject the all-powerful grace of God, and succeed in thwarting God’s purpose to save all souls? This occurs because God is loving and humble, so much so that He would never force anyone into Heaven. Even very sinful persons are offered every grace needed to repent and be saved, including the offer of final perseverance. But God knows from all eternity, from His place beyond Time, which sinners will choose not to cooperate with grace and not to repent. The offer of final perseverance stands before all human persons; some freely reject it and others freely accept it. Our all-powerful but humble God accepts each person’s choice.
— by Ron Conte