Muhammad and the Believers: At the Origins of Islam By Fred Donnner, Islam and Professor of Near Eastern History at the University of Chicago.
Book Referenced - CS Lewis, Mere Christianity - Chapter 8
I now come to that part of Christian morals where they differ most sharply from all other morals. There is one vice of which no man in the world is free; which everyone in the world loathes when he sees it in someone else' and of which hardly any people, except Christians, ever imagine that they are guilty themselves. I have heard people admit that they are bad tempered, or that they cannot keep their heads about girls or drink, or even that they are cowards. I do not think I have ever heard anyone who was not a Christian accuse himself of this vice. And at the same time I have very seldom met anyone, who was not a Christian, who showed the slightest mercy to it in others. There is no fault which makes a man more unpopular, and no fault which we are more unconscious of in ourselves. And the more we have it ourselves, the more we dislike it in others.
The vice I am talking of is Pride or Self-Conceit: and the virtue opposite to it, in Christian morals, is called Humility. You may remember, when I was talking about sexual morality, I warned you that the center of Christian morals did not lie there. Well, now, we have come to the centre. According to Christian teachers, the essential vice, the utmost evil, is Pride. Unchastity, anger, greed, drunkenness, and all that, are mere fleabites in comparison: it was through Pride that the devil became the devil: Pride leads to every other vice: it is the complete anti-God state of mind.
The Christians are right: it is Pride which has been the chief cause of misery in every nation and every family since the world began. Other vices may sometimes bring people together: you may find good fellowship and jokes and friendliness among drunken people or unchaste people. But pride always means enmity—it is enmity. And not only enmity between man and man, but enmity to God.
In God you come up against something which is in every respect immeasurably superior to yourself. Unless you know God as that—and, therefore, know yourself as nothing in comparison—you do not know God at all. As long as you are proud you cannot know God. A proud man is always looking down on things and people: and, of course, as long as you are looking down, you cannot see something that is above you.
Proverbs 16:18 - Pride goes before destruction and a haughty spirit before a fall.
1 Peter 1:5-5-7 - Clothe yourselves, all of you, with humility toward one another, for God, opposes the proud but gives grace to the humble. Humble yourselves, under the mighty hand of God so that at the proper time, he may exalt you, casting all your anxieties on him, because he cares for you.