Satan is not against good morals. He is opposed to Jesus Christ. A man can have good morals his entire life, yet he’ll go to hell when he dies. It’s Jesus Christ that everyone needs and the devil knows this more than all of us. The ultimate issue with Christianity is the authority of Christ, and the devil is attacking this authority by convincing people of practicing good morals alone. People are deceived into thinking that if they live a good life, they’ll receive God’s approval and attain Heaven. Only faith in Jesus Christ can save.