Even if the precise relations of substitution, representation, and liberation may be unclear, there is no reason all three cannot simultaneously inhabit Paul’s thought and biblical theology more broadly. It is striking how, when Paul comes to summarise his gospel in 1 Corinthians 15, he describes how Christ’s substitutionary death has dealt with sins (15:3) and in the same chapter also goes on to focus on the ultimate conquest of the “last enemy to be defeated,” death (15:26). Similarly, as was noted earlier, Colossians 2:13-15 juxtaposes forgiveness of sins with Christ’s stripping of the principalities and powers. In much the same way, the Heidelberg Catechism gives the following question and answer at its beginning, identifying the work of Jesus as both dealing with sins and effecting liberation from Sin.
Q. What is your only comfort in life and in death?
A. That I, with body and soul, both in life and in death, am not my own, but belong to my faithful Saviour Jesus Christ, who with his precious blood has fully satisfied for all my sins, and redeemed me from all the power of the devil.
In closing, one need only note that the choice between salvation as dealing both with “trespasses” or “debts” (plural) and with liberation from the power of (the) evil (one) was a choice apparently not faced by Jesus in his formulation of the Lord’s Prayer. Similarly, we need not be forced to opt either for Jesus’s substitutionary death, in which he deals with sins, or for a representative or liberative death, in which he deals with the power of evil. What therefore God hath joined together, let not man put asunder!
In other words: is Jesus our substitute or our representative? Yes.