Ezekiel 33:12-16

A blameless person who unrepentantly does something immoral has erred and not relented by turning from their error; the scope and depth of their past righteousness by logical necessity could not remove the fact that they have done what they should not.  Unless they come back to reason and justice, they have diluted their identity and betrayed reality without even trying to realign with the truth.  Someone could still be partly or even mostly rational and righteous.  This would not exempt them from the rest of their deeds.  Ultimately, not even returning to total perfection from the time of the sin onward would lift the guilt.

This is true with or without Christianity being true as well, and even if morality of any kind did not exist, reason would require that all of this would be correct if any moral obligations had been in existence.  For the most part, this conclusion is accepted as standard in evangelical circles, although it is because of tradition and blind assumptions that leads them to this rather than reason alone or reason and the Bible.  Verses like Ezekiel 33:12-16 do happen to very directly touch upon this, not that they are popular.  This passage states that the truly righteous can allow themselves to fall and will still in some way be judged as sinful (it is not clarified fully if they would lose their status before God and be cast into Gehenna unless they repented beforehand).

The former righteousness of someone who sins without repentance counts for nothing, Ezekiel 33:12 says.  Since the soul that sins deserves death (Ezekiel 18:4), whether the first death or the second (Matthew 10:28 addresses how both are death and not endless torture), the sinner will or should die despite being less guilty than a lifelong fool who has never once repented or devoted themself to what is just (again, Ezekiel 33:12).  Likewise, the sinner who repents will not have his or her past errors will not receive justice, but mercy (33:14-16).

In verse 14 and onward, God even says that someone he specifically promised would die would be spared if they quite literally turned from sin to justice.  They will not have their previous blunders counted against them if only they will not cling to them, in spite of how severe they were.  This promise of a deserved death is contingent upon how people choose to believe and behave.  Neither the uprightness of the once righteous or the depravity of the once wicked will be what determines their immediate standing with God in a sense.

The way that this relates to how one's righteous acts could never alter the past is that it is mercy to be offered salvation in the first place.  Restoring oneself to rationality and righteousness does not save one apart from this divine forgiveness.  Mercy and grace from God and commitment on the part of the redeemed individual are what contribute to salvation (Ephesians 2:8-10), each coming from different sources.  Otherwise, all the wicked would be burned into nonexistence of the mind (2 Peter 2:6) without the opportunity for redemption.  Repentance is a necessary component of commitment to Yahweh and Christ for any sinner and it is this that elevates them back to hope of perfection.