Another way to think about it is the fact that not all people born are saved. Whether one believes in libertarian free will or the free will of God, there are people who will not be saved, unless one is an universalist. It is no better to say that God elects whom he wants than to say He creates some whom he knows will never exercise their "free will" to "accept" him.
The latter makes some feel better because it exalts the creature and takes the "blame" off of God. Instead, what happens is that God is rendered impotent to the almighty will of the creature.
And the real cause of the difficulty is that we do not realize how exceedingly sinful and evil we really are and how holy God actually is. We deserve Hell. If God did not elect some, then none would be saved.
Maybe one approach to persuade could be to concentrate on the Total Deprativity of man in contrast to God's infinite holiness.
