What is justification?

Answer

Justification is an act of God's free grace, wherein he pardoneth all our sins (; ), and accepteth us as righteous in his sight (), only for the righteousness of Christ imputed to us (), and received by faith alone (; ).

Read the 6 proof texts (KJV)

Romans 3:24-25: ²⁴Being justified freely by his grace through the redemption that is in Christ Jesus: ²⁵Whom God hath set forth [to be] a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
Romans 4:6-8: ⁶Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works, ⁷Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered. ⁸Blessed is the man to whom the Lord will not impute sin.
2 Corinthians 5:19,21: ¹⁹To wit, that God was in Christ, reconciling the world unto himself, not imputing their trespasses unto them; and hath committed unto us the word of reconciliation. ²¹For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
Romans 5:17-19: ¹⁷For if by one man's offence death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ.) ¹⁸Therefore as by the offence of one [judgment came] upon all men to condemnation; even so by the righteousness of one [the free gift came] upon all men unto justification of life. ¹⁹For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous.
Galatians 2:16: Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
Philippians 3:9: And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith: