I first want to lay out what I believe Penal Substitution to be. This is what I've been taught growing up and is what is currently being taught at my (evangelical) seminary. As far as I can tell, this is the standard version of Penal Substitution. [However, I've heard that some in the Reformed camp see it significantly differently. I have yet to confirm this.] Once we have established what Penal Substitution is, I'll write a post on why I think it is wrong. Then I'll write a post on what I think the biblical alternative is.
The following is a list of the basic tenets of Penal Substitution (as I see them). Please let me know if anything is 1) missing, 2) incorrect, or 3) unnecessary. [I will update this post as appropriate comments come in.]
Justice (the Penal part):
J1. God is a God of (among other things) justice
J2. As a God of justice, God must punish sin
J3. All humankind has sinned
J4. The punishment for sin is death
J5. Therefore, God must punish all humanity with death.
Substitution (the Substitution part):
S1. Jesus was fully human yet sinless
S2. Jesus was crucified (i.e. punished/killed) though he was innocent
S3. Because he was innocent, His life was not forfeit. Therefore, Jesus was available to be punished/killed on behalf of humanity
S4. God punished/killed Jesus instead of us
S5. That is to say that Jesus died in our place
Results (the Salvation part):
R1. Jesus bore our sins on the cross
R2. At the same time, Jesus imputed to us His righteousness
R3. That is to say that Jesus substituted our sin with His righteousness, and vice-versa
R4. Because Jesus bore away our sin and imputed to us His righteousness, we are now justified before God
R5. We are saved from both sin and punishment
Corollaries (important, but not vital to Penal Substitution):
There is a one-to-one correspondence between God's wrath and God's punishment. God's wrath is expressed by God meting out punishment.
Am I missing anything? Can I make this more consistent? Any suggestions?