This is part 1 of 2. I started trying to write something about the idea of disinterested good, but realised I needed too much background. This is the background (here's the main point).
One of the big problems that the Church struggled with (largely unconsciously) for hundreds of years was the relationship between Christianity and Greek philosophy. Greek philosophy, in various forms, was widely and popularly held in the Roman Empire when Christianity was growing and spreading. It was easy for Christians to see that they should reject worshipping Caesar or Artemis; it was harder for them to see that there was a problem with Greek philosophy or to see what to do about it.
To create a huge generalisation, the Church in the Eastern Roman Empire, especially Alexandria, where Greek philosophy was strongest, tended to try to integrate philosophy and Christianity. In the West, they tended not to, spurred on by Tertullian's famous rhetorical question:
What has Athens to do with Jerusalem?
Tertullian of Carthage
The influence of philosophy on the early church wasn't wholly bad, but it did have lots of major problems. Almost all of the early heresies were caused by people putting their philosophical considerations ahead of what the Bible said. Early Church History (patristics) often concentrates on the East, because that was where most of the big arguments were. On the big questions that they argued about - how the Father, Son and Spirit could all be one God and how Jesus could be both human and divine - Tertullian in the West was hundreds of years ahead of the East. Even by 451, at the Council of Chalcedon, the big arguments in the East were only settled when Pope Leo of Rome wrote a letter explaining what they'd believed in the West for hundreds of years, which was what they ended up agreeing on. And then the arguments rumbled on even longer in the East, with the Syrian and Egyptian churches rejecting the compromise and splitting off.
But Rome wasn't immune either. During the Middle Ages, the western church got more and more influenced by Greek philosophy, especially Aristotelian metaphysics and physics and Ptolemaic astronomy to the point where they came to assume the place of dogma. Some of the difficulties in the Reformation with Luther et al and most of the difficulties in the Scientific Revolution with Galileo et al were because of the way that Aristotelianism had become entrenched as orthodoxy, and so to argue against it was seen as heresy.
Some of it is plainly wrong. The idea, for example, that God cannot suffer ("divine impassibility") is straight from Platonism rather than Christianity. If someone read the Bible with a mind open to the possibility of God being able to suffer, they would almost certainly conclude that God suffered in the person of Jesus. And yet through so much of the history of the church, that last sentence would have been immensely controversial.
All of which goes to show that it's easy for us to confuse parts of the surrounding worldview with the gospel, and then to end up elevating them as the truth. In part 2, I look at one bit of Greek philosophy that is still hanging on today.