Where to find the Body of Christ

Sal posts a letter below from someone considering becoming Catholic.
That letter reminds me how I had to puzzle about a certain question, somewhere along the way in the process of my conversion, namely:
Is it plausible that God has chosen to work this way, to reach humanity this way: through a real, visible community, a hierarchically-ordered community; through sacraments that involve human actions and real objects; through defined dogmas, church councils, and canonified scripture?
You’ll notice I said “plausible”, not “proven”. There are plenty of Christian doctrines that can’t be proven from prior knowledge, starting with the Trinity and the Incarnation. Why would the nature of the Church be any different?
At the time, the best I could say was — and remains: such a Church is like the Incarnation writ large. It is a visible, tangible presence of Christ in the world today, where the Word took flesh 2000 years ago, and where practically everything takes on flesh now: the washing of sin uses real water, prayer is represented with incense and kneeling, and the invisible realities of Heaven become visible through the statues and the icons. Even Jesus continues to be, in a sense, concretely present to us in our neighbor and our brother: sometimes the big brother who helps us, and sometimes the poor and little brother needing good from us; present in the one spouse bonded with the other; audible in the teachers and pastors who are ordained to bring us the Gospel (“he who hears you hears me”).
And I said, Yes, it’s plausible, it’s credible that God would work this way. We already know that He likes to work through matter: He invented it. In the Incarnation, He became it.
So here’s the Church with her weaknesses and limitations, and failures. Also in His earthly life, our Lord subjected Himself to having weakness and limitation, and even failures in a sense, for not everyone recognized Him.