From the Catholic Dictionary:
MOLINISM
Definition
The theory on grace and free will developed by the Spanish Jesuit theologian Louis Molina (1535-1600). It teaches that there is no built-in difference, but only an external accidental difference between sufficient and efficacious grace. God gives every person sufficient grace for all supernatural actions he or she is to perform. If one freely accepts the grace offered and cooperates with it, a salutary action is produced; this co-operation automatically makes a sufficient grace an efficacious one. If the free will refuses its co-operation, the grace remains sufficient only. God from all eternity foresees the free consent of the human will by his infallible foreknowledge of what a person would do with whatever grace he or she received. Why God chooses to give the person the precise grace he does, foreseeing whether that person will accept or reject it, is left as a mystery in God.
This is pretty close to the most common practical Protestant take. It’s sometimes humorously called Calminian.
C. S. Lewis, a Protestant who had dear Catholic friends, wasn’t surprised at all and even tried to symbolize it in his parable “The Great Divorce.” At some point the honestly humble Christian has to bow down before mystery vouched for in Scripture and testified in Christian experience and quit trying to puzzle it out in his own noodle. The divine logic can and does make the mortal brain go Tilt.