What did Christ have to do in order to become the head of the Body?
Christ had to die and suffer for us as members of His Body before He could become its Head. He had to die for us and suffer for us; the resurrection overcame that death, but He still suffered and died for the Body.
Les explains that the marriage relationship illustrates spiritual union with Christ: the husband is head of the wife, and Christ is the Head of the Church. In order for Christ to become Head of believers as members of His Body, He had to die. He had to die for us and suffer for us. The power of the resurrection overcame that death, but He nevertheless suffered and died for us as members of the Body. Les then applies this to husbands, who should be ready to die for their wives if necessary.