Here's the first Scripture reading at today's Mass (Exodus 19: 2-6):
In those days, the Israelites came to the desert of Sinai and pitched camp. While Israel was encamped here in front of the mountain, Moses went up the mountain to God. Then the LORD called to him and said, “Thus shall you say to the house of Jacob; tell the Israelites: You have seen for yourselves how I treated the Egyptians and how I bore you up on eagle wings and brought you here to myself. Therefore, if you hearken to my voice and keep my covenant, you shall be my special possession, dearer to me than all other people, though all the earth is mine. You shall be to me a kingdom of priests, a holy nation.”
With all their suffering, sinning, and exile since then, it is faith in that divine promise which has kept the Jewish people alive. A similar faith is needed to keep the Church, the New Israel, relevant in today's world.
On the whole, the ancient Israelites did not much like their vocation. Many fell away; even in the Sinai desert, those who didn't fall away had to endure "forty years" of wandering there—i.e., a heckuva long time—as the price of their grumbling half-faith. The Church as a whole, as People of God, resembles them; each of us sinners, as individuals, resembles them. God has called us out of slavery to a sinful world into a desert of dispossession where we can be free to hear his will for us and act accordingly as his priests for the world. He knows we cannot do that ourselves; so, by a continuous miracle of grace, Christ the One High Priest makes it possible for us. But on the whole, we aren't grateful. We think it's too hard, and unfair, and we didn't ask for this anyway. When the day's manna is gone, we're not sure the next day's will come. After all, you can't get something for nothing; at least the Egyptians (the world) kept us alive for doing their work for them. And though we may have left our former taskmasters behind, there's always those nasty Amalekites waiting near the next wadi. Anything good is taken by sweat and blood. Not even God's going to let us out of that. This business about faith and the law that Moses and Aaron (the saints and the hierarchy) keep selling us only makes everything harder. Let's just be realistic and get back to ordinary life like other, saner, happier people. No more Catholic hangups for us.
I'm keeping things general because the ways in which we do that, as both church and as individuals, are myriad. The Church's most visible temptation to be like the faithless Israelites is the temptation of the hierarchy to preserve the Church's institutional apparatus, and therefore their perks, at the expense of true witness—and therefore at the expense of those in and out of the Church who most need that witness. That's happened time and again in Church history, the most recent example being the systemic coverup of the sexual abuse of minors. We always see that, in the end, it doesn't work. But there are other sins; and our sins precisely as ordinary lay people all add up to a refusal to belong to a nation of priests. Priesthood is the business of the pros, it is thought; I'm just an ordinary person who wants what's rightfully mine and, having got it, to be left alone by the religious fanatics. They need to stay out of the bedroom and the boardroom.
The Jews have always had a "faithful remnant"—sometimes smaller, sometimes larger—to carry on in spite of everything. Sometimes they had to carry on in spite of persecution from members of the New Israel. We Catholics need to adopt a similar mentality. There needs to be a faithful remnant—which can sometimes embrace those outside the Church's visible boundaries—to preserve the fullness of the faith and the determination to live lives that don't water it down. In our day and age, there is no longer a Catholic culture to ensure that we can do that if we want. Our lives of faith, hope, and love must be intentional and countercultural. If we stop whining long enough to trust, the One High Priest will make up for our inability to do it ourselves.