[I]t is the righteousness of Christ, and not our own, on account of which we receive the pardon of sin; acceptance with God; are declared righteous, and have a title to the heavenly inheritance.

He also wrote:

John Gill differentiated between justification and pardon, when he wrote in 1750:

I readily allow that there is a very great agreement between justification and pardon, in their efficient, impulsive, and procuring causes, in their objects, or subjects, in their commencement, and manner of completion: the same God that pardons the sins of his people, justifies them, or accounts them righteous; the same grace, which moved him to the one, moved him to the other; as the blood of Christ was shed for the remission of sins, so by it are we justified; all who are justified are pardoned; and all who are pardoned, are justified, and that, at one and the same time; both these acts are finished at once, simul & semel, and are not carried on in a gradual and progressive way, as sanctification. But all this does not prove them to be one and the same, for though they agree in these things, in others they differ; for justification is a pronouncing a person righteous according to law, as though he had never sinned; not so pardon: it is one thing for a man to be tried by law, cast, and condemned, and then receive the king’s pardon; and another thing to he tried by the law, and, by it, to be found and declared righteous, as though he had not sinned against it.

Gill also wrote in 1778 in a tract:

Divines generally make justification to consist in the remission of sins, and in the imputation of Christ’s righteousness; which some make different parts; others say, they are not two integrating parts of justification, or acts numerically and really distinct, but only one act respecting two different terms, a quo & ad quem; just as by one, and the same act, darkness is expelled from the air, and light is introduced into it; so by one, and the same act of justification, the sinner is absolved from guilt, and pronounced righteous.

Many theologians continue to use the term “declared righteous” or “pronounced righteous” as the definition of justification.  Does the Bible use this terminology?  Certain translations (NET Bible) of Romans 5:1 translate, “being justified,” as “being declared righteous.”  If that’s the translation it’s in there, but if you look at the Greek words, those aren’t the Greek words.  The Greek words sound like what you read in the KJV:  ” Therefore being justified by faith, we have peace with God through our Lord Jesus Christ.”

Don’t get me wrong, I think “declared righteous” is fine for justification.  It could be a logical conclusion to the doctrine of imputation.  If we are “counted as righteous” like Abraham was, God is doing the counting, so He must be declaring believers righteous.  Does scripture say it?  I’m saying that the closest thing to the Bible saying, “declared righteous,” is in Romans 4:17:

The language of “declared righteous” could be found in the words, “God. . . calleth those things which be not as though they were.”  The verse doesn’t use “declared righteous,” but being “declared righteous” is ‘being called a thing which be not as though it was.’  This is a verse that says God does this.  Imputation of righteousness is God declaring someone righteous.  A few verses later, Romans 4:22-25 say:

Roman Catholicism has taught and still teaches that no one is righteous until he is found to be just.  He is not just through imputation.  He is just by cooperation with infused grace.  It’s still up to what that person does whether he will make it to heaven.  This false doctrine that entered Roman Catholicism came because of the Latin word for justification, iustificare.  Ficare in Latin means “to make.”  The Greek word for “justification” is God’s pronouncing someone righteous regardless of what he did.  The idea of “being made” righteous for justification came from the doctrine that man’s righteousness came by his cooperation, the wrong meaning of the Greek word.  The Catholic Encyclopedia, 1913, says concerning this:

Although the sinner is justified by the justice of Christ, inasmuch as the Redeemer has merited for him the grace of justification (causa meritoria), nevertheless he is formally justified and made holy by his own personal justice and holiness (causa formalis), just as a philosopher by his own inherent learning becomes a scholar, not, however, by any exterior imputation of the wisdom of God (Trent, Sess. VI, can. x). To this idea of inherent holiness which theologians call sanctifying grace are we safely conducted by the words of Holy Writ.  To prove this we may remark [on] the word justificare.

Louis Berkhof wrote about this in his Systematic Theology:

Our word justification (from the Latin justificare composed of justus and facere, and therefore meaning “to make righteous”), just as the Holland rechtvaardigmaking, is apt to give the impression that justification denotes a change that is brought about in man, which is not the case. In the use of the English word the danger is not so great, because the people in general do not understand its derivation, and in the Holland language the danger may be averted by employing the related words  rechtvaardigen  and  rechtvaardiging.

Perhaps you have considered whether justification is “being made righteous,” versus “being declared righteous.”  “Made righteous” is found once in the Bible and it is in Romans 5:19:

Being “made righteous” is different than being “declared righteous.”  Being “declared righteous” is justification and being “made righteous” is sanctification.  Someone justified will also be sanctified.  Man cooperates with God in sanctifying righteousness, but not in justifying righteousness.  He is made righteous in sanctifying righteousness.

Romans 5:19 uses the future tense of the verb, “shall many be made righteous.”  Romans 5:1, “Being justified” is an aorist participle, completed action.  In the past someone has been declared righteous and as a result in the future he shall be made righteous.  Through believing in Jesus Christ someone is justified, declared righteous, and he will be made righteous.  Sanctification is a process that continues until glorification.  Sanctification is actual transformation, metamorphosis.

Think two verses.  Romans 4:17, declared righteous, justification.  Couple with that verse, Romans 4:22-25.  Then, Romans 5:19, made righteous, sanctification.