From CS Lewis:
How did the Dark Power go wrong? Here, no doubt, we ask a question to which human beings cannot give an answer with any certainty. A reasonable (and traditional) guess, based on our own experiences of going wrong, can, however, be offered.
The moment you have a self at all, there is a possibility of putting yourself first – wanting to be the center – wanting to be God, in fact. That was the sin of Satan, and that was the sin he taught the human race… What Satan put into the heads of our remote ancestors was the idea that they could ‘be like gods’ – could set up on their own as if they had created themselves – be their own masters – invent some sort of happiness for themselves outside God, apart from God.
And out of that hopeless attempt has come nearly all that we call human history – money, poverty, ambition, war, prostitution, classes, empires, slavery – the long terrible story of man trying to find something other than God which will make him happy.
23 Then he said to them all: “Whoever wants to be my disciple must deny themselves and take up their cross daily and follow me. (Luke 9:23)
… fixing our eyes on Jesus, the pioneer and perfecter of faith. For the joy set before him he endured the cross, scorning its shame, and sat down at the right hand of the throne of God. (Hebrews 12:2)