Your theological questions can be answered with many great books.
• Know the Creeds and Councils by Bishop Justin Holcomb
• Know the Heretics by Bishop Justin Holcomb
• 27 Servants of Joy by Pr. John Piper
• Theological Retrieval for Evangelicals by Pr. Gavin Ortlund
• Lectures to my Students by Pr. Charles Spurgeon
• Confessions by St. Augustine
• Ancient Wisdom for the Care of Souls by Coleman Ford and Shawn Wilhite
• Systematic Theology by Wayne Grudem
• Bible Doctrine by Wayne Grudem
• What is Reformed Theology by R.C. Sproul
• Second London Baptist Confession of Faith 1689
• Westminster Confession of Faith
• On the Christian Life by John Calvin
• Institutions by John Calvin
• Ruined Sinners to Reclaim by David and Jonathan Gibson
• Biblical Theology by Andreas J. Köstenberger and Gregory Goswell
• Every Good Endeavor by Pr. Tim Keller
• The Mortification of Sin by John Owen
• Instruments in the Redeemer’s Hands by Pr. Paul Tripp
• Mere Christianity by C.S. Lewis
• Holiness by J.C. Ryle
• The Pursuit of God by A.W. Tozer
• A Gospel Primer for Christians by Milton Vincent
• Don’t Waste Your Life by Pr. John Piper
• How can I be sure I’m Saved? by Jeremy Pierre
• What if I don’t feel like going to Church? by Gunner Gunderson
• New City Catechism by Pr. Tim Keller
• Daily Liturgy Devotional by Douglas O’Donnell
• Be Thou My Vison by Jonathan Gibson
• O Sacred Head, Now Wounded by Jonathan Gibson
• Everyday Gospel by Pr. Paul Tripp
• New Morning Mercies by Pr. Paul Tripp
• Westminster Shorter & Larger Catechism
• Keach’s Catechism
• Sharing the Gospel with A Mormon by Tony Brown
• What is the Gospel? by Greg Gilbert
• Evangelism by Mack Stiles
• Are We Together? by R.C. Sproul
• Missions by Andy Johnson
• Discipling by Mark Dever
• Reaching your Muslim Neighbor with the Gospel by A.S. Ibrahim
• Expositional Leadership by R. Scott Pace & Jim Shaddix
• What do Deacons do? by Juan R. Sanchez
• Nine Marks of a Healthy Church by Mark Dever
• The Path to Being a Pastor by Bobby Jamieson
• The Reformed Pastor by Richard Baxter
• When Doctrine Divides the People of God by Rhyne R. Putman
• One Assembly by Jonathan Leeman