The Doctrine of Justification in Romans
Its Explanation (What it is)
Justification is defined by Webster as, "1.) ... a showing to be just or conformable to law, rectitude or propriety; vindication; defense; 2.) Absolution"; but most notably "4.) In theology, remission of sin and absolution from guilt and punishment; or an act of free grace by which G-d pardons the sinner and accepts him as righteous, on account of the atonement of Christ."  .
In the New Testament, the Greek noun most commonly translated justification is δικαίωμα (dikaioma) from the verb δίκαιος (dikaios) with a primary meaning "to render righteous or such he ought to be"  .
Justification would thus appear to be a state of being in which a human is completely free from any feelings of guilt or fear of condemnation that would ordinarily be brought on as a result of sin incurring the wrath of a holy G-d. In that sense, justification seems to be merely an abstract ideal and, for any honest thinking person, an unrealistic expectation.
Its Exigency (Why it’s needed)
Paul's epistle to the Romans begins by introducing three categories of humans: pagan, moral, and religious. He logically defines each group and demonstrates that regardless of external categorization, all are equal in standing before Yahweh.
The beginning of Romans chapter three paints an undeniably bleak picture; whether Jew or Gentile, there are none that are righteous regardless of whether they are under the law as given in the Torah or the law as dictated by their conscience. The next chapter (Rom. 4:15) includes the caveat that there is no escape clause, since the law brings wrath through its definition of transgression.
In verses 10-18, Paul quotes from Psalm 14:1-3, Psalm 5:9, Psalm 140:3, Psalm 10:7, Psalm 36:1, and Isaiah 59:7-8  , summarizing in one statement (Rom. 3:10) the universality and totality involved in transgression. Failure encompasses all of mankind and all attempts at righteousness as Paul states: "there is none righteous". As if this indictment were not sufficiently emphatic, he adds:"no, not one".
This condemnation reaches its climax in verse twenty, as Paul asserts that "by the deeds of the law there shall no flesh be justified in his sight". Righteousness is elusive to all and justification as a result is non-existent. The assertion is made against all flesh, with no differentiation or allowance for exemption made for any sex, race, nationality, religion or lifestyle; no one escapes this pronouncement. The assertion addresses being justified in the sight of G-d, with no attention paid to justification in the sight of any other. In other words, it matters not who you are and it matters not what anyone else thinks of you. What a grim perspective! Thankfully however, Paul does not stop at verse twenty.
Its Exercise (How it’s applied)
Having painted a dark picture with the grimmest of colors to this point, verse 21 introduces a gloriously bright new hue. The beginning of this change in tone is in two simple words: "But now". The weight sturdily and inexorably built through three chapters is effortlessly lifted and carried away in two syllables: "but now"! The law was the sternest of schoolmasters (Gal. 3:23-24), forever dictating and never satisfied in the past, "but now" comes graduation (Gal. 3:25). Only those that fulfilled the law to the letter (Rom. 2:12-14) were justified in the past, "but now" comes latitude. The law could only inform of transgression (Rom. 3:19-20) with no promise of deliverance, "but now" comes freedom.
This graduation, latitude and freedom comes through the righteousness of G-d Himself (verse 21). With hope for righteousness demonstrably found in no other source to this point in the epistle, this is supremely sweet news. This righteousness is not only utmost but unmistakably demonstrated; "manifested" in the King James Version is translated from φανερόω (phaneroo), which is the same word used after the resurrection of Christ when He suddenly appeared to the unexpecting disciples (Mark 16:12, 14; John 21:1, 14)  !
The righteousness previously unattainable is now available, but only through faith (verse 22). Verse 22 plainly states that even as all have equal condemnation under the law (verse 23), all have equal pardon through this channel (verse 24). This singular avenue affords the righteousness of G-d to be applied to or into ("unto" in verse 22 from εἰς or eis ) its adherents. It also overtakes them to be superimposed upon them ("upon" in verse 22 from ἐπί or epi ) to eclipse their baseness with His glory. Even as our sin was laid upon Christ (II Cor. 5:21), His righteousness is laid upon us. In other words, His righteousness is not simply added to our efforts in order to complete them, but it replaces them altogether.
This writer is reminded of his desire to be a faster runner in grade school. He was utterly convinced that if he could only obtain "faster shoes" that he would achieve this goal. He diligently saved his money until he was at last able to procure the brand name shoes that he desired, only to discover that new shoes did not supplant former legs! In the same way, since our righteousness is as filthy rags (Is. 64:6), His must cover ours completely rather than merely add to it.
Verse 24 develops this concept further in three parts: justification is 1) by His grace, 2) through redemption, and 3) it is in Christ Jesus. It is by His grace because it could never be earned (Rom. 3:28, 5:1, 8:33). It is through redemption, carrying the imagery of a ransom to be paid (as Yeshua spoke in John 8:34 and Paul later develops in chapter six of Romans). It is in Christ Jesus (I Cor. 6:11, Phil. 3:9), because He is the only One that Yahweh has declared worthy.
An additional (and refreshing) aspect of this justification is that it is given freely (verse 24). Although it cost the Savior dearly it is nonetheless free to us who were eternally unable to pay.
Its Effect (What it does)
Having the righteousness of G-d through Christ Jesus applied to us through faith in Him, we see in verse 25 in the third chapter of Romans an indication of the primary result of the process leading to justification. Paul asserts that Hashem exercises self-restraint (ἀνοχή or anoche , translated in KJV as forbearance) to affirm remission of sins. Remission is brought into English from πάρεσις (paresis ), which is only used in the Bible within this verse, but carries from its root a sense of tolerance through ownership. It is not that the Holy Almighty owns our sin, but rather owns responsibility for restraining His judgment upon One that He has already declared righteous.
The Apostle John touches on this concept (I John 1:9) when he states that G-d is faithful and just to forgive our sins when we confess; to simply forgive is not justice, until we take into account that our sin debt was paid upon the cross of Calvary (John 3:16-17). That idea is why Paul calls the death of Christ “propitiation” (Rom. 3:25). To quote one commentator, “The Bible word means to expiate by sacrifice. G-d has been propitiated through the work of Christ at Calvary; that is, His holiness has been so fully satisfied that He can now look again in favor on men.” 
Hence are men justified: not by our own works, but through despairing of them to the point of dependence upon the works of Him Whom G-d sent (John 9:4) to be our Redeemer. Through surrender to His path (John 14:6), we are adopted (Rom. 8:13-16) and made joint heirs (Rom. 8:17) to give us a future (Rom. 8:18) that we could not otherwise expect!
To quote a play on words heard in my youth, to be justified is as “just as if I’d” never sinned. To Him be all honor and glory both now and forever (I Tim. 1:17)!
(1) Webster, Noah. 1828 Dictionary of American English. e-Sword Version 7.9.8. Rick Meyers. Franklin, TN. 2008
(2) Strong, James. Exhaustive Concordance of the Bible. Thomas Nelson Publishers. Nashville, TN. 1995, 1996
(3) Guzik, David. "Study Guide for Romans 3." Blue Letter Bible. 7 Jul 2006. 15 Jun 2008.
(4) Strong, James.
(9) Phillips, John. Exploring Romans. The Moody Bible Institute of Chicago. 1969. Page 85
Hebrew-Greek Key Word Study Bible, King James Version, AMG Publishers, Chattanooga, TN, 1984, 1991
Romans: Everyman’s Bible Commentary, Alan F. Johnson, Moody Press, 1974,1976,1984,2000
The Teacher’s Outline and Study Bible: Romans Volume 1, Leadership Ministries Worldwide, Chattanooga, TN, 1994
New Topical Textbook, R.A.Torrey, E-Sword Version 7.9.8, Rick Meyers, Franklin, TN, 2008
Romans Curriculum; Lesson 4: The Provision of G-d’s Righteousness (Rom. 3:21-4:25), Moody Bible Institute, 2003