If you have been following the conversation in the comments section you may be interested to read this article by Greg Bahnsen taken from Monergism.
How can a guilty sinner avert the just condemnation and wrath of God? How can he be set free from the penalty he deserves? Paul wrote: “When the fulness of time came, God sent forth His Son, born of a woman, born under the law, so that He might redeem them who are under the law” (Gal. 4:4). In order to fulfill all of God’s promises and accomplish His saving design for men, Christ came to do a work of “redemption.”
And in Paul’s theologically authoritative conception of this redemption, it carried an unmistakably judicial and substitutionary character: “Christ redeemed us from the curse of the law, having become a curse for us” (3:13). Redemption or liberation is a setting free from a dreaded judicial reality: “the curse of the law.” And this act of setting us free was accomplished by a Substitute who assumed the judicial condemnation in our place: “having become a curse for us.” Christ’s death upon the cross was not simply some “equivalently terrible event” which replaces the infliction of the law’s judicial penalty (as “governmental” theories maintain), but rather the very bearing of that curse itself….
The redemptive work of Christ was clearly more than an act of representation or mediation, even though Scripture does look upon Jesus Christ as the federal representative of His people and as the only Mediator between God and men. In human transactions, a mediator or negotiator between adversarial parties may facilitate agreement, but he need not also — as a substitute for one of the parties (or both) — be the one who performs the service or pays the price involved in the eventual contract or resolution. An attorney can represent his client in a court of law, pleading before the bar, without also as a substitute for that client becoming the one who undergoes the punishment imposed by the judge. Christ our Savior did more than represent or mediate for us to God. Isaiah the prophet was granted by God a clear and poignant vision of this truth: “But he was wounded for our transgressions; he was bruised for our iniquities…. Jehovah has laid on him the iniquity of us all” (53:5-6). How shall God’s Righteous Servant “justify many”? Isaiah wrote: “it pleased Jehovah to bruise him; He has put him to grief,” making his life (or soul) an “offering for sin…. He shall bear their iniquities” (vv. 10-11).
To this the words of the New Testament add decisive confirmation. Christ was manifested at the consummation of the ages, says the author of Hebrews, “to put away sin by the sacrifice of Himself,” being “once offered up to bear the sins of many” (9:26, 28). By taking upon Himself the sins of His people, Christ bore the penalty of death which sin deserves. Jesus said it Himself when He referred to His coming death and interpreted it as “My blood of the New Covenant poured out for many for the forgiveness of sins” (Matt. 26:28). Peter writes that this “precious blood of Christ” was the means of our “redemption” (1 Peter 1:18-19). Redemption required that He die as our substitute. Thus Paul describes the Mediator as one who “gave Himself as a ransom on behalf of all” (1 Tim. 2:5-6), using a Greek word for “ransom” whose prefix gives it the literal sense of “substitute-payment.” This conspicuously mirrors the saying of Jesus Himself that He came “to give His life as a ransom [release-price] in the place of many” (Mark 10:45).
The doctrine of penal substitution could be expunged from the Biblical witness only by a perverse and criminal mistreatment of the sacred text or a tendentious distortion of its meaning. What else could Peter have meant by writing to believers in the church that “Christ suffered for you”? The Greek preposition (“for”) has the sense of “in your behalf” or “for your sake.” Was it simply for the sake of a moral example, so that those who “suffer unjustly” (v. 19) might “follow His steps” (v. 21)? Is that the end of the matter (exemplary suffering) or is that not rather the moral application of the fundamental saving significance of Christ’s suffering? Surely the manner in which Christ died can be a model and even a motivator without at all securing forgiveness or securing ethical integrity; history is full of paradigmatic and pathos-engendering martyrs, while men familiar with them nevertheless continue under the bondage of sin and subject to God’s wrath. Peter’s explanation of the sense in which Christ, the innocent one, suffered “for” us extends to this precious truth: “who bore our sins in His body upon the tree” (v. 24). The substituting of the innocent in the place of the guilty, for the sake of rescuing the guilty from condemnation, comes out just a few verses later when Peter declares: “Christ also suffered for sins once, the righteous for the unrighteous, in order that He might bring us to God” (3:18).
We see from the above that Christ’s atoning death was intended to have an objective effect upon a wrathful Judge (God) and not simply a subjective reverberation in the heart of believers. “Moral influence” theories minimize the significance and uniqueness of the cross by making it merely a compelling example of God’s great love, emotionally moving men to live self-sacrificially by imitation. Other stories of martyrdom can evoke pathos, but Scripture sets forth the work of Christ as of unparalleled importance. If it was not important because it secured the favor of God, the crucifixion is debased into a senseless act of showmanship.
Similarly, “governmental” theories portray Christ’s suffering, not as a penal substitution, but simply a penal example of sin’s dreadful and tragic nature so that divine pardon (“bypassing” the demand for the sinner’s punishment) will not have the effect of weakening the honor or enforcement of God’s moral demands in the eyes of the public. Society would not take seriously the need to be morally governed by God unless, in the place of punishing sinners as He threatened, God substituted some great measure which was unpleasant and filled with grief. Such speculation, like the moral influence theory, also undermines the significance and uniqueness of the cross. In order to continue providing a deterrent against forgiven men lapsing into sin, God might occasionally repeat penal examples like Christ’s suffering throughout history (the more recent and relevant, the better after all) — which is utterly unthinkable in New Testament theology wherein there is absolutely no need for Christ “to offer Himself up often” since His redemptive work was performed “once and for all” (Heb. 9:12, 25-28). On the deterrent (“sin-prevention”) interpretation of the atonement, the crucifixion is debased into a distasteful act of manipulation.
The theological perspective of the Biblical writers, prophets and apostles both being witness, is that one who was perfectly righteous stood in the place of those who are unrighteous in God’s sight, bearing the curse or penalty of their sin by dying in their place, in order to set them free from condemnation and secure their eternal benefit. There is no other way, as Peter indicates, for sinners to be “brought back to God.” This makes maintaining the purity and truth of the gospel as the good news about judicial and substitutionary atonement a matter of infinite personal importance. It makes the self-conscious rejection of this central Biblical theme a matter of dreadful consequence. “For we know Him who said ‘Vengeance belongs unto Me, I will recompense’…. It is a fearful thing to fall into the hands of the living God” (Heb. 10:30-31). Our only hope is that Christ’s saving death is received by God precisely as a “sacrifice for sins” (cf. v. 26).