Why did he die? To make an atonement for sin? Yes, but the reason given here is that we should no longer live for ourselves but for him. He died to make us holy.
Have you an ambition for self? You are a believer, you have trusted in Christ and repented of your sin, you have come to him on the basis of his shed blood and his atoning death, and you have given him your life. But right now there is a consuming ambition which steals your priorities and drives your life, and it is all for you, for your benefit. That cannot be. ‘He died for all, that they which live [in him] should not henceforth live unto themselves,’ putting their own objectives first, and their own purposes first, ‘but unto him which died for them, and rose again’ for them.
That is one of the purposes of the communion service, the Lord’s Supper. We remember he died for us. I died on Calvary when he took my death, my punishment; I died there so that I may live. How can I live any other way but for him and for his mission in this world?
Some people try to drive a wedge between the two parts of the verse. ‘He died for all’ on the one hand, that ‘they which live’ on the other hand, as though he died for everyone but only the people who were converted and lived benefit from his death. No, the ‘all’ is still the redeemed. There is no artificial distinction. He died for all believers, ‘that they which live should not henceforth live unto themselves, but unto him which died for them, and rose again.’