But he that doeth wrong shall receive for the wrong which he hath done: and there is no respect of persons.
Note 9 at Col 3:25: Some have interpreted Col 3:24-25 as saying that people get exactly what they deserve or earn, according to their actions. That's not exactly what Paul was saying.
Many passages of Scripture show that salvation is a gift that is offered to the least deserving (Ro 4:5). If our actions were required to earn salvation, no one would be saved (Ro 3:23). So, those who receive the gift of salvation by putting faith in Christ (Eph 2:8) "receive the reward of the inheritance" (Col 3:24), which is Christ's inheritance. Although we don't deserve it, we receive all the provisions of Christ's inheritance, because we have become joint-heirs with Him.
However, this verse is speaking of those who do not receive the free gift of salvation. They will be held accountable for their actions, and there will be no mercy shown (see note 10 at this verse).
Note 10 at Col 3:25: Without Christ's redemptive work in people's lives, they will have to stand and give an account for all the wrong that they have done. Those who have not received salvation by faith will not be shown favoritism or partiality in the Day of Judgment--"the wrongdoer will be paid back for the wrong he has done" (this verse, Revised Standard Version).
The Apostle Paul's discourse before Felix rendered a similar statement - "And as he reasoned of righteousness, temperance [self-control], and judgment to come, Felix trembled [he was afraid], and answered, Go thy way for this time; when I have a convenient season, I will call for thee" (Ac 24:25, brackets mine).
Although God's salvation is "free," it must be received (Joh 1:12). Those who do not receive God's free gift will be punished eternally (Ro 6:23).