Recommended: "Why Jesus Had to Die"

Jeff at Old Testament for the Church looks at "Why Jesus Had to Die." He finds part of the answer in the corporate identity of Israel:

Years ago, I remember hearing, almost apologetically, from one of my seminary professors that Israel after all did think about individuals. Looking back now, I took this to mean that poor ignorant Israelites were not as enlightened as we in the West. Now, I think just the opposite. We poor ignorant Westerners have forgotten what it means to belong to a group larger than me.

We in the West tend to see things, including the truth of the Scriptures, in terms of the individual. Jeff explains:

Our proclivity towards viewing most things individually has clouded our ability to accept that one person could die for all people. This is why we have a hard time understanding why Jesus had to die.

Yet the fluidity between the corporate and individual in biblical faith is central to Jesus' atoning death. Jeff has written a fine series of brief, readable, informative posts. I recommend you read them all: Part 1, Part 2, and Part 3.