Perhaps someone can diagnose the fallacy, but I simply describe what happens.
If we take the legendary (though younger than often realized) “TULIP” of “the five points of calvinism,” the fallacy deals with the fourth point.
Properly understood, “Irresistible Grace” means that there is a grace from God that is irresistible–that those effectively chosen for eternal life will be invincibly drawn by God to his salvation and be made to stand firm in the Faith to the end.
The hypercalvinist fallacy is to claim from this that there is no such thing as resistible grace. Anyone who teaches what the Bible says about God’s grace given commonly to both the elect and the reprobate (those chosen for eternal life and those not chosen for eternal life) is treated as an attack on irresistible Grace.
But it is nonsense. An affirmation of irresistible grace in no way implies a denial of resistible grace. Furthermore, the Bible speaks of resisted grace without ambiguity. Indeed, the Biblical doctrine of eternal conscious punishment as “fire” is premised on resistible grace. God is loving and gracious and man responds to God’s love and grace with resistance and ingratitude.
Remember the warning attached to the Second Commandment:
I, the LORD your God, am a jealous God, visiting the iniquity of the fathers on the children, on the third and the fourth generation of those who hate Me.
God’s wrath is His jealousy. Hell is his burning jealousy. Song of Solomon 8.6:
Jealousy is as severe as Sheol;[or Hell]
It’s flashes are flashes of fire,
The very flame of the LORD.
Wrath is fierce and anger is a flood,
But who can stand before jealousy?
God is loving and gracious. God pursues sinners. God offers forgiveness. But He will not be patient forever. And the very reason Hell is hot, is because such a great love has been spurned.
Thus, for example, sacraments can be objective means of grace to elect and non-elect alike, and yet work toward the damnation of those who do not believe.