164 Considering the need, the men who are shouldering this responsibility are far too few in number, yet they are deserving of the highest recognition from society, and We rightfully honor them with Our public praise. We call upon them to persevere in their ideals, which are of such tremendous benefit to mankind. At the same time We are encouraged to hope that many more men, Christians especially, will join their cause, spurred on by love and the realization of their duty. Everyone who has joined the ranks of Christ must be a glowing point of light in the world, a nucleus of love, a leaven of the whole mass. He will be so in proportion to his degree of spiritual union with God.
Source: Pacem in Terris (Vatican.va)