Finally, those who have not yet received the Gospel are related to the People of God in various ways (cf. St. Thomas Aquinas, Summa Theologica, Part 3, Q.8, Art. 3, Reply 1) ... Nor is God remote from those who in shadows and images seek the unknown God, since He gives to all men life and breath and all things (cf. Acts 17:25-28), and since the Savior wills all men to be saved (cf. 1 Timothy 2:4). Those who, through no fault of their own, do not know the Gospel of Christ or His Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience - those too may achieve eternal salvation (cf. Letter of the Holy Office to the Archbishop of Boston). Nor shall divine Providence deny the assistance necessary for salvation to those who, without any fault of theirs, have not yet arrived at an explicit knowledge of God, and who, not without grace, strive to lead a good life. Whatever good or truth is found amongst them is considered by the Church to be a preparation for the Gospel (cf. Eusebius of Caesarea, Praeparatio Evengelica, 1.1) and given by Him Who enlightens all men that they may at length have life. But very often, deceived by the Evil One, men have become vain in their reasonings, have exchanged the truth of God for a lie and served the world rather than the Creator (cf. Romans 1.21, 25). Or else, living and dying in this world without God, they are exposed to despair. Hence to procure the glory of God and the salvation of all these, the Church, mindful of the Lord's command, "preach the Gospel to every creature" (Mark 16.16) takes zealous care to foster the missions. (Second Vatican Council, Lumen Gentium - Dogmatic Constitution on the Church, 16, November 21, 1964)
Those of Good Will must be brought to the Church by preaching to them. But God will also assure through His Providence that those of Good Will are brought to the Church, despite their explicit ignorance of the Gospel in their present state. God wishes the salvation of every man, so if He has prepared a man for the reception of the Gospel, that man WILL receive the Gospel.
Again, the Catechism of clear:
851. Missionary Motivation. It is from God's love for all men that the Church in every age receives both the obligation and the vigor of her missionary dynamism, "for the love of Christ urges us on," (2 Corinthinas 5:14; cf. Apostolicam actuositatem 6, Roman Missal 11). Indeed, God "desires all men to be saved and to come to the knowledge of the truth" (1 Timothy 2:4); that is, God wills the salvation of everyone through the knowledge of the truth. Salvation is found in the truth. Those who obey the prompting of the Spirit of truth are already on the way of salvation. But the Church, to whom this truth has been entrusted, must go out to meet their desire, so as to bring them the truth. Because she believes in God's universal plan of salvation, the Church must be missionary.
So you see, the virtuous man of good will is already on the path of salvation, because God has prepared him to receive grace. BUT, the Church must also go out and find these people. The annals of the Missions are filed with wonderful stories that make it very clear that this will always happen.