For whom did Christ die? Everyone. Everyone from Adam to the last person who will be born before Christ returns. In my tradition, we often call this "objective justification," that is, the death and resurrection of Christ have objectively taken care of everyone's justification. All have been died for. God has reconciled all things to himself (Col. 1:20). Atonement for all has been done for all, *whether they believe it or not.* I often compare this to the sun shining. The sun is shining down on all. Now, of course, some can close their eyes or stay inside and flatly deny that the sun is shining down on all, but their *subjective* unbelief or denial does not negate the *objective* fact. It's still true.
When is Christ's work of atonement given to someone? Again, in my tradition, we often call this "subjective justification." This is when the objectively accomplished, universal work of Christ is subjectively given to the person who believes. Faith is the hand that receives it. They become Christians, receive forgiveness, life, salvation, etc. To continue the analogy from above, subjective justification is when they are ushered outside by the Spirit to bask in the warmth of the sun or have their eyes opened to see it. What had been true all along becomes "real" for them as they receive it.
Written by Chad Bird, 1517 Scholar