The moral influence theory of the atonement maintains that the death of Christ was not necessary as a means of removing sin. Instead, the loving sacrifice of Christ, as such a wonderful and selfless act, influences the hearts and minds of those who hear about it and moves them to repentance and trust in Christ. It was first proposed by Peter Abelard (1079-1142).
The problem with the moral influence theory is that it violates the Scriptures which say that no one seeks for God (Romans 3:10-12) and that the unbeliever cannot understand nor receive spiritual things (1 Cor. 2:14) and that unbelievers are slaves of sin (Romans 6:14-10). In other words, those who are enslaved to sin cannot simply be "influenced and moved" to repentance. If the moral influence there is correct and we are influenced by the selfless sacrifice of Christ, then why do we have Scriptures that say that we're granted the act of believing (Philippians 1:29) and that we're granted repentance (2Timothy 2:25) and that we cannot come to Christ unless it has been granted to us from God the Father (John 6:65). Furthermore, the death of Christ was substitutionary (Isaiah 53:4-6, Matthew 20:28) and a legal act (Col. 2:14) since the atonement for sin is the fulfillment of the law. After all, sin is breaking the law of God (1 John 3:4).
Therefore, the moral influence theory is not correct.