God covers your sin with the righteousness of Christ, imputing to you Christ’s righteousness in His declaration of His justification.
>>What verse in scripture explicitly says what you wrote?
The idea of imputation is derived from late medieval secular philosophy rather than from the Bible.
http://www.freerepublic.com/focus/f-religion/2826044/posts
Imputed righteousness would have been a foreign concept to the earliest Christians.
Except that is exactly what the Word of God says:
Romans 4:5-8
But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness. Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works, Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered. Blessed is the man to whom the Lord will not impute sin.
Romans 4:9-12
Cometh this blessedness then upon the circumcision only, or upon the uncircumcision also? for we say that faith was reckoned to Abraham for righteousness. How was it then reckoned? when he was in circumcision, or in uncircumcision? Not in circumcision, but in uncircumcision. And he received the sign of circumcision, a seal of the righteousness of the faith which he had yet being uncircumcised: that he might be the father of all them that believe, though they be not circumcised; that righteousness might be imputed unto them also: And the father of circumcision to them who are not of the circumcision only, but who also walk in the steps of that faith of our father Abraham, which he had being yet uncircumcised.
Romans 4:21-23
And being fully persuaded that, what he had promised, he was able also to perform. And therefore it was imputed to him for righteousness. Now it was not written for his sake alone, that it was imputed to him;
James 2:23
And the scripture was fulfilled which saith, Abraham believed God, and it was imputed unto him for righteousness: and he was called the Friend of God.
The word imputed, in the Greek is "logizomai", and means:
1) to reckon, count, compute, calculate, count over
a) to take into account, to make an account of
1) metaph. to pass to one's account, to impute
2) a thing is reckoned as or to be something, i.e. as availing for or equivalent to something, as having the like force and weight
b) to number among, reckon with
c) to reckon or account
2) to reckon inward, count up or weigh the reasons, to deliberate
3) by reckoning up all the reasons, to gather or infer
a) to consider, take into account, weigh, meditate on
b) to suppose, deem, judge
c) to determine, purpose, decide
This word deals with reality. If I reckon (logizomai) that my bank book has $25 in it, it has $25 in it. Otherwise I am deceiving myself. This word refers more to fact than supposition or opinion.
So, I would disagree that imputed righteousness would have been a foreign concept to the earliest Christians, seeing as Paul taught it and the concept was also spoken of in the Old Testament as well.