What Relationship Does Penal Substitution Have on a Christian's Power over Sin?

Harding University in Searcy, Arkansas hosted Dr. Craig in February of 2018 for a series of lectures and discussions. Speaking at the Bible majors chapel for their Spring lecture, Dr. Craig talks on the question "Is Penal Substitution Biblical?” Following his lecture, Dr. Craig responds to this question regarding PSA and victory of sin for a follower of Jesus.