The theme is God's commissioning unworthy men to preach his saving word. In our jaded, increasingly post-Christian culture, the need for that is ever more urgent. It can and should be met by Christians in general and the clergy in particular. In a Catholic context, we need to focus on the particular means by which laity and clergy respectively must do so.
It's been noted for decades that the ambient culture in the West is no longer Christian, or even all that friendly to Christianity. That problem is not yet as acute in the U.S. as in Western Europe or Canada, but we are headed down the same path. Thus committed Christians, including Catholics, can no longer count on the Faith's being transmitted by osmosis, or even on what theologians call "implicit faith." That is especially evident in the breakdown of the traditional family, which has developed almost as much among believers as unbelievers. The only kind of Christianity that will last will be intentional and missionary. It will be intentional because, when it is not, it will continue dissipating in face of the secular culture's momentum. It will be missionary because Christianity is inherently a missionary religion. When Christians do not act accordingly, their religion becomes a museum piece for the culturally conservative minority and an increasingly inconvenient bit of cultural baggage for everybody else. But even though Catholic laity and clergy must both be intentional and missionary, the ways in which each must be that differ from each other. And those ways can be understood by contrast with how things generally are in the Church.
The laity are supposed to be the Church in and for the world. In fact, about 99% of the Church just is the laity. But most either don't know that or, if they do, don't really get it. For them, as for the rest of the world, "the Church" is really an institution or organization consisting of the clergy and their co-workers, working out of expensive physical plants called "churches" and "chanceries" and sponsoring social services that, while important, could in principle be replaced by government. Incredibly, the notion that the Church is mostly just us, the Body of Christ bringing Christ home to ourselves, our families, friends, co-workers, and wider communities, is still largely foreign to most Catholic laity--even half-a-century after Vatican II, which stressed "the universal call to holiness" and the corresponding importance of the laity. Most still instinctively identify themselves as Americans, or professionals, or spouses or parents, or even as fans of their sports teams, before identifying as Catholics. Religion is just one more compartment of life, one more box to check, whose main purpose is to provide fire insurance for the next life--assuming, of course, that fire insurance is needed, which more and more Catholics seem to disbelieve.
Over the same period of time, the situation hasn't been all that much better among the clergy. Normally the problem is not such ignorance of the Faith as results from and reinforces garden-variety worldliness, but another kind of worldliness. In my fifty-odd years, I have observed thousands of Catholic clergy and religious in many different environments. Aside from a public commitment to celibacy (with some canonical exceptions), the most common feature I've observed among them is not theological orthodoxy or personal holiness, but how comfortable they are. They have no worries about employment: Jobs and people come to them, sometimes in profusion. None have the sort of worry about health care that many laity do: They can expect adequate care paid for by the self-insured churchly entities to which they belong for life. They have no families to struggle to care for; in the majority of cases, even their major personal expenses such as housing and cars are paid for by contributions, not salary. And despite the sex-abuse-and-coverup scandal, clergy and religious still command respect and a presumption of good will from those they are meant to serve.
None of those things are bad in themselves; arguably, they facilitate the mission of the professionally religious. But one thing they entail is that the penalties for indifference, incompetence, or malfeasance are usually far less severe for clergy and religious than for laity. If you're a priest or religious, you basically have to be a convicted criminal to lose your employment and health care, because what you have is really an unusual "vocation" rather than a job, and such a vocation can be lived out through many different jobs and relationships. The result is that much indifference, incompetence, and malfeasance go unpunished and sometimes even unnoticed. That has allowed priests and religious to become too comfortable. It promotes the sort of worldliness evinced by the many bishops who covered up sexual abuse, and protected the abusers, so that the boat would not be rocked and the Church's prestige would be maintained. We've seen how that's worked out. And don't even get me started on the failure of so many priests and religious to inspire laity to be Church, as opposed to paying, associate members of the organization. They have not failed because their preaching is bad; sometimes it's good. They have not failed because they don't work hard enough; many work hard indeed. They have failed simply because their comfort is more evident than their holiness. That disparity does not go unnoticed.
Read and meditate on today's Bible readings. They apply equally to the professionally religious and to lay people. That they apply to the professionally religious needs no explanation: Such people just are those who have been specially called and commissioned by God to bring his truth and love to the rest of the Church. But laity need to realize that they are that too, for the world as a whole. We are "a chosen people, a royal priesthood, a holy nation, God's own possession, that you may declare the praises of him who called you out of darkness into his wonderful light" (1 Peter 2:9). As Pope John Paul II reminded us, we are to "put out into the deep water" in faith, trusting that we will be successful "fishers of men," starting with ourselves. I find that a far more inspiring vision of life than any accomplishments of mine that the world can recognize and approve. The latter are purely contingent matters. The former is what we are called to be in God, for God, so that we can become gods.