Romans 14:12 says: "So then every one of us shall give account of himself to God" and Matthew 12:36 says: "But I say unto you, that every idle word that men shall speak, they shall give account thereof in the day of judgment." Both of these verses state that individuals must some day, before God, give an account of every idle word as well as an account of himself.
The very thought of this is frightening because all of us are sinners and "fall short of God’s glory" (Romans 3:23). Plus our "righteousness" before God is like filthy rags" (Isaiah 64:6). What does all of this mean for Christians?
The Bible teaches us that when God’s forgives us our sins, He removes them as far as the "east is from the west" (Psalms 103:12) and that under the new covenant when one accepts and obeys the gospel "God is merciful to our unrighteousness and our sins and iniquities He remembers no more" (Jeremiah 31:34).
If a Christian is forgiven and God remembers their sins as if they never happened, what is there to account for?
Paul in Romans 6 says that we are dead to sin if we are "in" Christ Jesus. In fact, that is the only way you and I can possibly be "dead to sin." If we are "in" Christ and walk with Christ and He forgives us our sins (I John 1:7) what are we to give an account for?
"But in accordance with your hardness and your impenitent heart you are treasuring up for yourself wrath in the day of wrath and revelation of the righteous judgment of God, who "will render to each one according to his deeds": eternal life to those who by patient continuance in doing good seek for glory, honor, and immortality; but to those who are self-seeking and do not obey the truth, but obey unrighteousness -- indignation and wrath, tribulation and anguish, on every soul of man who does evil, of the Jew first and also of the Greek; but glory, honor, and peace to everyone who works what is good, to the Jew first and also to the Greek. For there is no partiality with God" (Romans 2:5-11).
You appear to assume that judgment only involves looking at the wrongs a person has done. But God stated that He will look at both the good and evil that we have done. "For we must all appear before the judgment seat of Christ, that each one may receive the things done in the body, according to what he has done, whether good or bad" (II Corinthians 5:10). The parable of the talents shows the king examining the results of both his faithful and unfaithful servants (Matthew 25:14-30).
A second assumption appears to be that once a person is a Christian, there are no more sins, but that too is false. "If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar, and His word is not in us. My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous" (I John 1:8-2:1). Notice the "if"'s throughout this passage. God will forgive and remove our sins, but only if we meet His conditions. Being dead to sin does not mean that those in Christ never sin. Rather sin isn't the Christian's master.