Why read about Catholic Theology? Because each new thing learned and meditated about God is a new reason for loving Him. The Joy and excitement of Theological knowledge is identical to the joy and excitement of any other love: you just cannot explain it to someone who has not experienced it!
“Jesus answered: it is written: Man shall not live on bread alone, but on every word that comes from the mouth of God”. - Matthew 4:4
We are surrounded by millions of people who are starved of this “Food” for their souls. We, as practicing Catholics have to overcome this spiritual starvation! We must share our love for God to our friends, relatives and our neighbors! For it's not good for us, or for our children, to be the sane minority, living in a society that has lost all contact with God!
But how can we share this knowledge if we ourselves know nothing or little about God? Some people think this is quite heavy stuff! Do not get discouraged, we can start with Roman Catholic Theology for beginners.
We should read all Roman Catholic Theological books accompanied by the Holy Scripture. Why? Because the Holy Scripture has a wonderful power to make the Truth come alive in our souls!
It's always right to start with the Gospels and after that the Act of the Apostles. Later we can read some of st. Paul's epistles.
I would especially advise to read the Corinthians, Galatians, Philippines, Ephesians, Romans and Colossians. But sooner or later we should read the whole Scripture!
In Theological studies we can learn about the nature of Man, the Sin at our origin, the Supernatural Life (the Holy Life/Spirit of God). Get a true understanding of the Blessed Trinity!
Learn about and love the Holy Trinity and let The Father, The Son and The Holy Spirit come and live in our Hearts.
Take courage and dive deeper into the knowledge of God, read sound Catholic Books.