According to Romans 4:25, Jesus was delivered up to death on the cross for our sins and then raised again to life for our justification; so His death is both a substitutionary sacrifice to propitiate a God angry at the sins of man as well as the vehicle through Whom a man born again is able to live his life.
Paul continues the theme in Romans 5:6-10 in which he points out that since we have been justified by His Blood – that is by participating in His death through partaking of our own death of self – we shall be saved from the wrath of God since, having been reconciled to God by the death of Jesus, which we emulate in the death of self, we will most assuredly be saved by sharing in His resurrected life.
Christ’s death was a death for sinners and a reconciliation with God for those in enmity against Him, but also salvation for those reconciled through the divine impartation of a share of the life of Christ which He, as their substitute, obtained for them from His death.
The problem that Christians have with the epistle to the Romans is not a theological one but a moral one; if we sincerely desire release from the power of sin, it is within reach. Were men and women utterly willing to submit themselves to the workings of the cross and have those workings wrought in them and applied in their lives, there would be a profound shaking in the kingdom of darkness; the frontiers of hell would recede.
The cross is to the Christian life what the root is to the tree; the source of life and nourishment without which the tree can produce no fruit and will die.