The apostle Peter recounts how Jesus continually suffered and was reviled at the hands of His enemies, and then He reveals what Jesus did in response–He kept on committing Himself (the force of the verb tense) to God (1 Pet. 2:23). Two chapters later, Peter was continuing to address 
the present reality of the followers of Christ also continually suffering and being reviled at the hands of their enemies. He called upon them to respond as Jesus did–keep on committing (the force of the verb tense) your souls to God (1 Pet. 4:19).
So, what does it look like to keep on committing your soul to God? Peter added these three words: “in doing good” (4:19). Peter had emphasized doing good in the face of evil throughout the book (2:12, 14, 15, 20; 3:6, 11, 16, 17). While the world will treat you with contempt, in an effort to get you to stop “doing good,” the will of God is for us to use that as an opportunity to do even more good…for Him! Don’t let the world control you! Respond to their evil like Jesus did–keep on committing yourself to God by keeping on doing good!