The first question for each and every single one of us is “Who is God?” And because we live in the age of biblical fulfillment (i.e., the New Testament), on this side of the cross, resurrection, and ascension, the most relevant question—one which is the the equivalent to “Who is God?” —that ought to be our starting question, “Who is Jesus?”
All the other questions about “me” and “you” are the wrong place to start.
The second question—and there is a second follow-up question to the first—still isn’t about “you” or “me,” though. This second, follow-up question stems from the NT teaching that Jesus is the head and the church is His body. So the second (relevant) question is “What is the church?”
Now once these two questions are clear and the answers grappled with, then we can proceed to “Who am I?” But not before.
Now, go reread the words of Saint Augustine above.