The Oxford English Dictionary defines substitution as "the putting of one person or thing in the place of another." When one looks at the concept of substitution in theology it refers to the death of Christ as substitutionary. Another way to describe substitution is by the word vicarious from the Latin word vicarius meaning "one in place of another." To be precise, it is best to describe Christ’s death as a penal substitution. When we use the adjective "penal" to the word substitution we are placing the concept of substitution into the context of moral law, guilt and retributive justice. J. I. Packer explains that penal substitution is an "instrument for conveying the thought that God remits our sins and accepts our persons into favour not because of any amends we have attempted, but because the penalty which was our due was diverted onto Christ. The notion which the phrase ‘penal substitution’ expresses is that Jesus Christ our Lord, moved by a love that was determined to do everything necessary to save us, endured and exhausted the destructive divine judgment for which we were otherwise inescapably destined, and so won us forgiveness, adoption and glory." In summary, penal substitution is the death of Christ bearing the punishment justly due sinners by the guilt of their sins being imputed to Him (set down to His account) in such a way that He representatively bore their eternal punishment.

The concept of substitution is pictured in the life of Abraham and Isaac in Genesis 22. God told Abraham to take the promised seed, Isaac, and sacrifice him in a place where God would show him. In this significant event Abraham, the father, gives up his son as a sacrifice while Isaac, the son, willingly lays down his life. God demonstrates the significance of this event when He intervenes and provides the ram as a substitute. All the important features of Christ’s penal substitutionary sacrifice are typically foreshadowed in this event.

The concept of penal substitution is also presented in the Old Testament sacrificial system. One of the most explicit statements on the substitutionary principle in the Old Testament is found in Leviticus 17:11, "For the life of the flesh is in the blood, and I have given it to you on the altar to make atonement for your souls; for it is the blood by reason of the life that makes atonement." Here God indicates that the sacrificial animal in its death takes the place of the death due the offerer and makes atonement for his sin. Many of the sacrifices required the offerer to lay his hands on the animal before he would sacrifice it. The meaning of this ritual is explained in the Day of Atonement (Lev. 16). The high priest would lay his hands on the second goat and confess the sins of the people. Then the second goat would be lead into the wilderness to symbolize the removal of the sins of the people. The goats in the Day of Atonement typify the penal substitutionary sacrifice of Jesus Christ.

Penal substitution can also be seen in the feast of Passover (Ex. 12). The Passover typified redemption with the blood of the lamb. Applying the blood of the lamb on the two door posts and the lintel of the house lifted the curse of death of the first-born. God said "...when He sees the blood...the LORD will pass over the door and will not allow the destroyer to come into your houses to smite you" (Ex. 12:23). The blood representing the life of the animal became the substitute for the death of the first-born. What is pictured in the Passover is actually accomplished in the death of Christ. Paul says in Galatians 3:13, "Christ redeemed us from the curse of the Law, having become a curse for us...." It is interesting that our Lord used the time of the Passover to institute the Lord’s Supper, which is given to remind Christians of Christ’s substitutionary work for us.

The sacrificial system is the heart of the Jewish worship and religious life. The priests at the temple offered the burnt offering every day both morning and evening. Sacrifices were commanded at most feasts (Passover, Pentecost, Day of Atonement, Tabernacles and others). There were sacrifices for the redemption of the first-born, sins committed by individuals, certain ceremonial cleansing (i.e. after childbirth and leprosy) and dedications. What the sacrificial system symbolized is vividly expressed in Isaiah 53 and explicitly promised in Jeremiah 31:31-37 by the New Covenant. Therefore, this symbolic picture of penal substitution was woven into the fabric of the Jewish mind who knew the Old Testament. This is why the herald of the Messiah, John the Baptist, could trumpet one statement and communicate the penal substitutionary work of Jesus Christ. "Behold, the Lamb of God who takes away the sin of the world" (Jn. 1:29).

Penal substitution is clearly established in the New Testament by the use of two Greek prepositions anti and huper. M. J. Harris summarizes the possible meanings for anti: (1) "for" denoting equivalence—one object is set over against another as its equivalent (Mt. 5:38; 1 Cor.11:15) (2) "for" denoting exchange—one object, opposing or distinct from another; or one object given or taken in return for the other (Rom. 12:17; Jn. 1:16) (3) "for" denoting substitution—one object, is given or taken instead of the other (Mt. 2:2; Lk. 11:11). It is this last meaning that is clearly seen in Matthew 20:28, "just as the Son of Man did not come to be served, but to serve and to give His life a ransom for (anti) many" (see also Mk.10:45). The evidence is so overwhelming on this point that those who object to the doctrine of penal substitution usually concentrate their effort on the preposition huper because most of the passages in the New Testament that involves substitution use the preposition huper. Yet, it needs to be stressed that the doctrine of penal substitution is established by the preposition anti.

The two predominant meanings for the preposition huper in the genitive case are in behalf of (representation) and in the place of (substitution). The substitutionary sense of huper is seen in the following non-theological verses. In Philemon 13 which says, "whom I wished to keep with me, that in your behalf (or place—huper) he might minister to me in my imprisonment for the gospel." In Colossians 1:7 Epaphras represented Paul and preached in his place. In John 11:50-51 and 18:14 Caiaphas declares "it is expedient for you that one man should die for (huper) the people...." Harris concludes from these verses that huper "denotes substitution, not simply benefit or representation, since Caiaphas’ remarks that such a death ‘for the people’ would ensure that ‘the whole nation’ did not perish.... That is, politically the death of the one (as a scapegoat) would be a substitute for the death of many." Dr. Bruce Waltke demonstrates that both Romans 9:3 and Philemon 13 are important non-theological verses, which demonstrate substitution in the New Testament. All the above verses demonstrate the substitutionary sense of huper with no theological "axe to grind" except for possibly John 11:50-51.

With huper established as a preposition that does express the concept of substitution, one can turn to 2 Corinthians 5:21 and Galatians 3:13 to demonstrate that this substitution is penal. In 2 Corinthians 5:21 the guilt of our sins are place on Christ when it says, "He made Him who knew no sin to be sin [in our place] (huper) that we might become the righteousness of God in Him." In Galatians 3:13 the curse of our sins was placed on Christ when it says, "Christ redeemed us from the curse of the Law, having become a curse for (huper) us—for it is written, ‘Cursed is everyone who hangs on a tree.’" Finally, 1 Timothy 2:6 strongly supports penal substitution when the preposition anti is attached to the compound word antilutron (ransom) with the preposition huper. "[Christ Jesus] who gave Himself as a ransom (antilutron) for (huper) all.…"

We must conclude from our study of huper that the prepositions anti and huper have overlapping meanings. Both prepositions are used to convey the doctrine of penal substitution. Therefore, we cannot dismiss the doctrine of penal substitution just because the preposition anti is not used. It seems that the writers used huper because it was more flexible. They could express both meanings of benefit and substitution together and at once. The preposition huper has a broader meaning then anti, but they overlap to convey a substitutionary idea.

Penal substitution strikes at the very core of the gospel. If the concept of penal substitution is not clear in your salvation presentation then you have a weak and unclear gospel. In other words, penal substitution is the essential core of the gospel.

Sin is the issue in salvation for it offends a holy God, condemns men eternally to hell and destroys lives. For God to be just, every sin must be paid for. Either men will eternally pay for their sins in hell or a qualified substitute must pay for it and, therefore, eternally free that individual from punishment. If you and I were in prison and on death row (looking to be executed soon), and you felt compassion on me and would like to be my substitute and take my place at the electric chair, do you think the chief officer of the prison would let you take my place so I could go free? No, he would not! Why? Who then would take your place for you deserve to be punished in the same way? The only way anyone could be considered to take another’s place in prison on death row is if he is not guilty of a crime and is not on death row. In a sense we are all born into this world on death row for we have all sinned in thought, word and deed and we all deserve to be punished by God in hell forever. However, God has provided a penal substitute for us who has never sinned in thought, word or deed. Jesus Christ, the sinless Son of God, took upon himself flesh and came to earth and never sinned in any way becoming the only person qualified to be our substitute.

The suffering the Son of God took at Calvary goes far beyond the physical. He suffered the full force of God’s wrath for every sin of every person who will believe in His saving work. Paul says, "He made Him who knew no sin to be sin on our behalf that we might become the righteousness of God in Him" (2 Cor. 5:21). Therefore, Jesus Christ’s substitutionary death and resurrection has purchased salvation for all who will come to Him through faith alone (Rom. 10:9-10). Salvation does not come by being a good person, doing good works, being religious, partaking the sacraments, belonging to a specific local church, thinking my good works will outweigh my bad works nor believing in Christ plus doing good works! It is not what I do, but what has been done that is important. I must believe in what has been done in my place. The Bible says, "For by grace [an undeserved gift] you have been saved through faith; and that not of ourselves, it is the gift of God; not as a result of works, that no one should boast" (Eph. 2:8-9). Thank God we have in Jesus Christ a penal substitute!