"And he died for all, that those who live might live no longer for themselves but for him who for their sake died and was raised" (2 Corinthians 5:15 RSV).
I think you need to include verse 14 to understand the entire idea: "For the love of Christ controls us, because we are convinced that one has died for all; therefore all have died." Paul is writing in defense of himself against rumors and other teachers whose understanding of the message of Jesus Christ is different from his own. His point here is that once we accept the Truth of the Christ, as Jesus Christ taught and demonstrated, we will be changed in important ways. Our lives will be enfolded in "the love of Christ"—that is, the new awareness of our true spiritual nature. That understanding is the gift available to us through the love, mercy, and demonstration of Truth Jesus accomplished. It is as the Christ, in his fullest expression of the spiritual Truth of who we all are, that he moved through the illusion of death to show the Truth of eternal life. We don't have to die to remember that Truth; we can believe and accept his example.