According to a concept called the "sleeper effect," when someone allows their credibility to momentarily decline, they actually engender long-term trust.

That's why leaders who sprinkle in self-effacing humor are often more trustworthy than charismatic ones. Moses, the leader God chose to deliver his people from the most powerful ruler in the known world, was described as "a very humble man, more so than any man on the face of the earth" (Numbers 12:3).

But humility isn't the end-all of leadership. It must be tempered with impartiality and authority. God himself exemplifies this kind of impartial leadership in the book of Amos. God's actions in this and other prophetic books confirm a philosophy that runs throughout the Bible: The highest form of leadership integrity is impartiality.

When you're impartial, you're fair, just, unprejudiced and unbiased. Impartiality produces honesty. It makes a leader predictable – people know how you'll respond to issues. A judge's wise ruling flows out of ...