1 Corinthians 15:21 For since death came by man, the resurrection of the dead also came by man.
1 Corinthians 15:22 For as in Adam all die, so also in Christ all will be made alive.
It has been claimed that the above words have already been fulfilled. Nevertheless, as we look around us, it is very obvious that all who have died in Adam have not yet been made alive.
Thus, those who argue that this scripture was fulfilled in the first century imagine and presume that the death is spiritual death and that being made alive means to be made alive "spiritually". "Spiritual death" is usually defined as being separated from God. While sin does indeed separate one from God, this separation, however, is not the condemnation. Even if it was, we still do not find that everyone has been "made alive" spiritually. Thus, the claim would have to be that by means of Christ, some -- not all -- have been made alive spiritually, while the rest remain spiritually dead.
If spiritual death -- separation from God -- was actually the wages of sin, this would mean that the condemnation that came upon Adam was spiritual death, not physical death. Usually, it is argued that Adam would have died physically even if he had not disobeyed, which would mean that Adam was condemned to death before he was condemned.
If the condemnation that came upon Adam for sin was spiritual death, it would further mean that the wages of sin of Romans 6:23 would have to be spiritual death, and the death in Romans 5:6-8,12-19 is spiritual death. It would mean, if one were apply this idea consistently in Paul's words, that in order to pay wages of sin, Jesus died, not a physical death, but a spiritual death.
Since, without the intervention of Jesus' sacrifice for sin, Adam's condemnation would have been eternal, if that condemnation was spiritual death, then to pay the wages of sin for all mankind Jesus would have to be spiritually dead - eternally separated from God.
However, there is no doubt that when the scripture says that Jesus "died for our sins" (Romans 5:8; 1 Corinthians 15:3), that this does not mean that Jesus is now dead spiritually forever, but that he actually died physically for sins -- his body, his flesh is now sacrificed and remains dead for all eternity. -- Luke 22:19; 1 Timothy 2:5,6; Hebrews 10:10; 1 Peter 3:18.
Nevertheless, in this age, those who belong to Christ are indeed reckoned as justified and thus reckoned as having already been made alive as new creatures. They are reckoned as already living in the time when the age in which Satan is god has passed away, and all things are made new. (2 Corinthians 4:4; 5:17; Revelation 20:1-3; 21:1-5) Thus, we read that they have tasted of the powers of the age to come. -- Hebrews 6:5.
Although already reckoned as alive -- saved by hope, however, they still look to that "age to come" in which Satan will no longer be "god" for the full deliverance into eternal life. -- Mark 10:30; Romans 8:24,25.
That the "age to come" has not yet come can be seen in that the heathen are still being deceived by Satan. -- 2 Corinthians 4:4; Revelation 20:1-3.