Yet, even in their reply to this, or the like, they are not at a loss for a contentious rejoinder. For they assert that God, if He had been so pleased, might have forcibly drawn those, who were not inclined to yield, to accept the Gospel message. But where then would have been their free will? Where their virtuous merit? Where their meed of praise from their moral directors? It belongs only to inanimate or irrational creatures to be brought round by the will of another to his purpose; whereas the reasoning and intelligent nature, if it lays aside its freedom of action, loses at the same time the gracious gift of intellect.
For upon what is he to employ any faculty of thought, if his power of choosing anything according to his inclination lies in the will of another? But then, if the will remains without the capacity of action, virtue necessarily disappears, since it is shackled by the enforced quiescence of the will. Then, if virtue does not exist, life loses its value, reason moves in accordance with fatalism, the praise of moral guardians is gone, sin may be indulged in without risk, and the difference between the courses of life is obliterated.
For who, henceforth, could with any reason condemn profligacy, or praise sobriety? Since every one would have this ready answer, that nothing of all the things we are inclined to is in our own power, but that by some superior and ruling influence the wills of men are brought round to the purpose of one who has the mastery over them. The conclusion, then is that it is not the goodness of God that is chargeable with the fact that the Faith is not engendered in all men, but rather the disposition of those by whom the preaching of the Word is received.
Source: The Great Catechism (New Advent)