Why did Jesus have to die?

Responses (offsite)

Online booklet from RBC Ministries explains why Christ died
J. Hampton Keathley III explains the theology of salvation
Glenn Miller's series of articles on sacrifice in the Bible and Jesus' death on the cross
Lenny Esposito addresses the question of how Jesus could be punished as a sinner

See also the article on the death of Christ in Baker's Evangelical Dictionary (article by Francis Foulkes).