And Charles Spurgeon eloquently makes the case for the indispensable connection between Jesus Christ's perfect obedience and his righteousness imputed to us:
The Reformed tradition bases the doctrine of the imputed righteousness of Christ, even his active obedience, on such passages as Romans 5:12-21 (WCF 6.3, 11.1; cf. Heidelberg Catechism, Q/A 60). Why, for example, does Paul contrast the disobedience of Adam with the obedience of Christ? Paul writes, "For as by the one man's disobedience the many were made sinners, so by the one man's obedience the many will be made righteous" (Rom. 5:19). As John Murray explains, "The parallel to the imputation of Adam's sin is the imputation of Christ's righteousness. Or to use Paul's own terms, being 'constituted sinners' through the disobedience of Adam is parallel to being 'constituted righteous' through the obedience of Christ." Clearly, Romans 5:19 restates what Paul has stated in the previous verse: "Therefore, as one trespass led to condemnation for all, so one act of righteousness leads to justification and life for all" (Rom. 5:18).There is no mistaking the parallel between Christ's obedience, which is righteousness, and the imputation of this righteousness to the believer. Commenting on the abiding significance of Genesis 15:6 and the imputation of righteousness, Paul writes: "That is why his faith was 'counted to him as righteousness.' But the words 'it was counted to him' were not written for his sake alone, but for ours also. It will be counted to us who believe in him who raised from the dead Jesus our Lord" (Rom. 4:22-24). Note here the English Standard Version translates the Greek word logizomai as "counted," which the King James Version translates as "imputed." Here Paul taps into the ancient stream of the special revelation of the Pentateuch, the first five books of the Bible, to argue for the imputed righteousness of Christ, and arguably also has other passages such as Isaiah 53 in mind when writing these things: "Out of the anguish of his soul he shall see and be satisfied; by his knowledge shall the righteous one, my servant, make many to be accounted righteous, and he shall bear their iniquities" (Isa. 53:11; cf. 2 Cor. 5:19-21).
The promises in the Word of God are not made to suffering; they are made to obedience. Consequently, Christ’s sufferings, though they may remove the penalty of sin, do not alone make me the inheritor of the promise. “If You will enter into life,” said Christ, “keep the commandments” (Matthew 19:17). It is only Christ’s keeping the commandments that entitles me to enter life. “The Lord is well pleased for his righteousness’ sake; he will magnify the law, and make it honorable” (Isaiah 42:21). I do not enter into life by virtue of His sufferings – those deliver me from death, those purge me from filthiness; but entering the enjoyments of the life eternal must be the result of obedience. As it cannot be the result of mine, it is the result of His, which is imputed to me….See what Christ has done in His living and His dying, His acts becoming our acts and His righteousness being imputed to us, so that we are rewarded as if we are righteous, while He was punished as though He had been guilty.
Justification then comes to sinners as an act of pure grace, the foundation of it being Christ’s righteousness. The practical way of its application is by faith. The sinner believes God and believeth that Christ is sent of God. [He] takes Christ Jesus to be his only confidence and trust; and by that act, he becomes a justified soul. It is not by repenting that we are justified, but by believing; it is not by deep experience of the guilt of sin; it is not by bitter pangs and throes under the temptations of Satan; it is not by mortification of the body, nor by the renunciation of self; all these are good, but the act that justifieth is a look at Christ. We, having nothing, being nothing, boasting of nothing, but being utterly emptied, do look to Him Whose wounds stream with the life-giving blood. As we look to Him, we live and are justified by His life. There is life in a look at the crucified One—life in the sense of justification.