Aside from Scripture reading and dipping in and out of Wayne Grudem's Systematic Theology, I'm presently reading Augustine's "City of God."
It's such a joy to read from a fellow saint, who, though long dead, still speaks. It's a great reminder that "nothing is new under the sun," especially when it comes to the enemies of the Gospel and the ready defense we are called to have when the world asks just what the heck is up with us that we have hope in hopeless times.
Though separated by 17 centuries and different sides of this present age, Augie and I share in the communion of saints, in a common citizenship in Heaven. We stand before the throne of grace in the "city of the living God" robed not in our own righteousness but that of our faithful Lord Jesus (Heb. 12:22-24) who has cleansed us with His blood:
But you have come toe Mount Zion and to the city of the living God, f the heavenly Jerusalem, and to g innumerable angels in festal gathering,23 and to h the assembly  of the firstborn who arei enrolled in heaven, and to j God, the judge of all, and to the spirits of the righteous made perfect, 24 and to Jesus,k the mediator of a new covenant, and to l the sprinkled blood m that speaks a better word than the blood of Abel.Please pray that the Lord speaks to me through His servant Augustine insofar as Augustine rightly divided the Scripture and that I grow in my thirst for and capability to wrestle with the collective wisdom of the writings of the saints who have preceded me into the presence of the Lord.