Classical Theism holds not just to God’s existence, but God’s simplicity, immutability, impassibility, eternality, incomprehensibility, and so on. The tradition is found in pagan thinkers such as Plotinus but is defended throughout the Christian tradition (Augustine, Aquinas), Jewish Tradition (Maimonides), Muslim Tradition (Avicenna), and others. I myself was converted to theism by the arguments for Classical Theism, specifically. For some historical background, Ed Feser summarizes the reasons why Classical Theism is critical to the theistic project, serving as the only non-arbitrary explanatory stopping point for why composite-contingent thing exists and not nothing instead. (Feser has his own roundup on CT here.)
Enough introduction. What follows are a list of resources defending classical theism.
First resource: My $1 eBook How to Think About God presents a contemporary Thomistic argument for God’s existence. I also defend the position against contemporary attacks, including charges of modal collapse, contingent knowledge, and more.
I also have multiple, extended podcast conversations
establishing classical theism and refuting objections, including:
The 5 Ways of Thomas Aquinas with Dr. Gaven Kerr
Aquinas’s Way to God (The De Ente Argument) with Dr. Gaven Kerr
Arguing Essence and Existence with Dr. Gaven Kerr
Defending the Doctrine of Divine Simplicity with Chris Tomaszewski
How Reason Can Lead to God with Dr. Josh Rasmussen
How to Think About God on Classical Theism (my interview with John DeRosa)
Some additional articles/blogs include:
God’s Impassibiltiy and Knowledge of Sin
Safeguarding Divine Simplicity with Bernard Lonergan
My Introductory Article on Aquinas’s Way to God on Word on Fire