The heart has its rationalizations, which reason did not abjure

"Probity, Sir, does not permit me to deny the force of these arguments.  I am persuaded that he is a dishonest man [who] treats with apparent contempt the reasons of his adversaries when he feels the whole force of them in the depths of his heart; this would be to lie to others as well as to oneself.  Thus, when we together examined all the miracles of antiquity, we have neither disguised nor treated with contempt the reasons of those who deny them, and we only opposed, in good Christian fashion [(en bons chrétiens)], the faith to arguments.  Faith consists in believing what the understanding cannot, and it is in this that the merit lies.
"But Sir, in being persuaded by faith of things which appear absurd to our intelligence, which is to say, in believing what we do not believe, we are protected from making this sacrifice of our reason in the conduct of life.
"There have been those who have said, to the contrary, 'You believe things incomprehensible, contradictory, impossible because we have ordered you to; so do things unjust because we have ordered you to.'  These people reason wondrously.  [For] certainly he who is within his rights to render you absurd is within his rights to render you unjust.  If you do not oppose to orders to believe the impossible the intelligence that God has placed in your mind, you are not obliged to oppose to orders to do evil the justice that God has placed in your heart.  Once [you have allowed] one faculty of your soul to be tyrannized, all the other faculties must be equally so.  And it is this which has produced all the religious crimes with which the earth has been inundated."

"La probité, monsieur, ne me permet pas de nier la force de ces arguments. Je suis persuadé qu'il est d'un malhonnête homme de traiter avec un mépris apparent les raisons de ses adversaires, quand on en sent toute la puissance dans le fond de son coeur: c'est mentir aux autres et à soi-même. Ainsi, quand nous avons examiné ensemble les miracles de l'antiquité, nous n'avons ni déguisé ni méprisé les raisons de ceux qui les nient, et nous n'avons opposé, en bons chrétiens, que la foi aux arguments. La foi consiste à croire ce que l'entendement ne saurait croire; et c'est en cela qu'est le mérite. "Mais, monsieur, en étant persuadés, par la foi, des choses qui paraissaient absurdes à notre intelligence, c'est-à-dire en croyant ce que nous ne croyons pas, gardons-nous de faire ce sacrifice de notre raison dans la conduite de la vie.
"Il y a eu des gens qui ont dit autrefois: Vous croyez des choses incompréhensibles, contradictoires, impossibles, parce que nous vous l'avons ordonné; faites donc des choses injustes parce que nous vous l'ordonnons. Ces gens-là raisonnaient à merveille. Certainement qui est en droit de vous rendre absurde est en droit de vous rendre injuste. Si vous n'opposez point aux ordres de croire l'impossible l'intelligence que Dieu a mise dans votre esprit, vous ne devez point opposer aux ordres de malfaire la justice que Dieu a mise dans votre coeur. Une faculté de votre àme étant une fois tyrannisée, toutes les autres facultés doivent l'être également. Et c'est là ce qui a produit tous les crimes religieux dont la terre a été inondée."

Voltaire, Letter 12 On miracles (1795), translation mine. Tout Voltaire (whence the French); 1797, pp. 150-151.
But of course Pascal (to whom Voltaire himself is of couse here responding) had already replied more than thirty years before Voltaire was even born. Reason and the heart lie on different levels.
But of course Pascal stole this from Plato, Republic 9, 582a ff. (the second argument: "Which of the three men has most experience of the pleasures we mentioned?" The one ruled by the love of learning (the rational part). He has more experience of the pleasure of being honored than the one ruled by the love of honor (the spirited part), just as the one ruled by the love of honor has more experience of the pleasure of profit than the one ruled by the love of profit (the appetitive part, because the "appetites for food, drink, sex, and all the things associated with them . . . are most most easily satisfied by means of money" (580d-581a)) and 583b ff. (the third argument: "apart from those of a knowledgeable person, the other pleasures are neither entirely true nor pure but are like a shadow-painting").