Agreed. A close second for me is Systematic Theology by Wayne Grudem. It helped me understand the Bible and put the things I was reading into categories. It'

Agreed. A close second for me is Systematic Theology by Wayne Grudem. It helped me understand the Bible and put the things I was reading into categories. It's a thick book, but very readable. If you want something a bit smaller, there are two thinner books that are a summary of the original: * Introduction to systematic theology (the discipline, not the book): https://www.thegospelcoalition.org/article/whats-systematic-theology-and-why-bother/ https://www.thegospelcoalition.org/article/whats-systematic-... * Introductory book: Christian Beliefs * Mid-Level: Bible Doctrine * In Depth: Systematic Theology