From the Catholic Encyclopedia:
The universality of grace is a necessary consequence of the will to save all men. For adults this will transforms itself into the concrete Divine will to distribute "sufficient" graces; it evidently involves no obligation on God to bestow only "efficacious" graces. If it can be established, therefore, that God grants to the three classes of the just, sinners, and infidels truly sufficient graces for their eternal salvation, the proof of the universality of grace will have been furnished. Without prejudice to this universality, God may either await the moment of its actual necessity before bestowing grace, or He may, even in time of need (e.g. in vehement temptation), grant immediately only the grace of prayer (gratia orationis sive remote sufficiens). But in the latter case he must be ever ready to confer immediate grace for action (gr. operationis s. proxime sufficiens), if the adult has made a faithful use of the grace of prayer.
Our religion is one of witnessing, of evangelizing. We are called by our baptism to go out an make disciples of all nations. This is no small statement from God, but a command. External preaching is essential. Grace builds on hearing the Word of God. Catholics greatly differ from the Protestants on this point. They do not believe that humans are really redeemed, that is, truly justified. Therefore, grace is more of a once and for all experience.
As to growing in holiness, yes, some Protestants do believe in that, but the universality of grace does not demand continual repentance and renewal, merely a recognition of one's personal salvation. We know it is presumptuous to rest and not keep striving after the goal.
God will not refrain in extraordinary cases from miraculous intervention in order to save a noble-minded heathen who conscientiously observes the natural moral law. He may either, in a miraculous manner, depute a missionary to him (Acts, i, 1 sqq.), or teach him the revealed truth through an angel (Cardinal Toletus), or he may come to his assistance by an interior private revelation. It is clear, nevertheless, that these different ways cannot be considered as everyday ordinary means. For the multitude of heathen this assistance must be found in a universal means of salvation equally independent of wonderful events and of the preaching of Christian missionaries. Some modern theologians discover it in the circumstance that the two dogmas mentioned above were already contained in the primitive supernatural revelation made in Paradise for all mankind. These truths were subsequently spread over the whole world, survive, as a meagre remnant, in the traditions of the pagan nations, and are orally transmitted from generation to generation as supernatural truths of salvation. The knowableness of these dogmas by unaided reason does not constitute an objection, for they are simultaneously natural and revealed truths. Once the condition of external preaching (cf. Rom., x, 17: "fides ex auditu") has thus been fulfilled, it only remains for God to hasten to mans assistance with his supernatural illuminating and strengthening grace and to initiate with the faith in God and retribution (which implicitly includes all else necessary for salvation) the process of justification. In this manner the attainment of the state of grace and of eternal glory becomes possible for the heathen who faithfully co-operates with the grace of vocation. However all this may be, one thing is certain: every heathen who incurs eternal damnation will be forced on the last day to the honest confession: "It is not for want of grace, but through my own fault that I am lost."
This last sentence would be denied by psychologists and social scientists who daily blame circumstances or nuture for people's sins, denying the fact that nature has been redeemed.
Later today, I shall look at efficacious grace.