The most influential Christian theologian and philosopher is St. Augustine. He was heavily influenced by Neo-Platonic, Hellenistic ideas, and Stoicism. This is the most simple explanation I could give because it's a complicated subject. Basically classic greek philosophy was attempting to find the "good life." be it through the best government (The Republic by Plato) or through intuition (Socrates). What Augustine did was use this kind of philosophy, which was already engrained in Roman culture, and change the "good life" to mean "object of love/city of god". Now the good life was no longer here on Earth, but rather through the grace and love of God. What Augustine did was flip greek philosophy around and used their very own arguments against them. Now the good life was irrelevant because the only way to achieve it was now through God which therefore meant that Greeks philosophers efforts were misplaced because it is impossible to achieve the good life here on Earth. Sorry, this would take a couple essays to explain how and why this change logically makes sense and was actually genius. If you want to blow your mind listen to this and this. They're only 20 minutes each