"Penal substitution" is a theological concept that refers to Jesus taking the punishment for humanity's sins. It suggests that God punished Jesus in our place, allowing us to be forgiven and have a relationship with Him. Full definition
As for this post, are you questioning his portrayal of penal substitution theory? (nakedpastor.com)
This is called the «appeasement theory» or «penal substitution theory» of the atonement, and is the idea that the death of Jesus appeased the wrath of God. (redeeminggod.com)
In the two chapters on soteriology we find a number of them, for example, a denial of the redemptive dimension of the Incarnation, a purely forensic understanding of the doctrine of justification, and a narrow focus on penal substitution in the doctrine of atonement. (firstthings.com)