The Journey to Truth is an Experience (download below). I'll be referring you to this text as we go through the year, reading just certain pages each month. It's a helpful text to understand what we are trying to do with the Youth Theology meetings and Discussion meetings.
"Journey for October:
91-96 "The Encounter"
Doctrinal support for October
Another resource is the United States Catholic Catechism for Adults. I've attached below the first chapter, which you can look at in preparation for October discussion.