"Pride goes before destruction, and a haughty spirit before a fall."
The meaning of this verse is pretty clear. Pride has repeatedly been shown in the scriptures to be a surefire way to cook your own goose. This is evidenced by instances such as the episode of the Tower of Babel in Genesis, where mankind tried to build the said tower in a flagrant plan to eclipse God's power and commune with their false gods, or rather, the demonic realm. As a result, God immediately took a preemptive measure against their plan by confusing their language, which lead to the dispersal of mankind across the face of the Earth, as God had originally intended. Likewise, in the book of Daniel, King Nebuchadnezzar of the Chaldean Empire gloried in his accomplishments without giving credit to God, and as a result was given the mind of a lunatic for a time. Happily, however, he repented and sought God's approval, resulting in his restoration to power. Another story involving a very different king did not end so nicely. In Acts 12, King Herod Agrippa I, after being hailed as a "god," failed to deflect such blasphemous praise, and as a result was struck dead by an angel of God before being "eaten by worms." In sum, pride, arrogance, and haughtiness are wholly undesirable traits which should be avoided at all costs. Indeed, elsewhere in Proverbs, in Chapter 6, one of things the Lord "hates" is "haughty eyes." But why does God hate pride so much? God utterly detests a prideful heart because it indicates a person's essential worship of his own achievements, and by extension, himself, rather than worship of God.
(Frequent readers may have noticed that I did not quote the ESV Study Bible on this verse. This is because I have now decided to write original opinions on verses, which I believe make for more substantial and stronger content than a mere quotation of another source.)
In church today, the pastor talked about the judgement of God. Specifically, he said that we should not judge others hypocritically, that is, condemning the sins of others while secretly sinning ourselves. Thus, God, being a just and kind person, will judge the "secrets of men" and we therefore need to repent. In the High School service, the guest pastor gave a talk on Romans 12, and how we are to love our enemies and to not harbor grudges or hatred toward others.