Preach Christ to the world, not moral codes. When the believing is right, right living, including moral excellence, will follow.

Believer, the world already knows that sin is abhorrent to God and has dangerous consequences; this is why most sins/immoral acts are committed in secret. The law/moral codes for living is already emblazoned on the hearts of the world. Preaching morals or things like "stop fornicating or else there will be consequences" to the world that God so loved is not the message of Christ and cannot save the sinner. Paul said it well in Romans 7:18-

"For I know that nothing good lives within the flesh of my fallen humanity. The longings to do what is right are within me, but will-power is not enough to accomplish it."

This doctrine of preaching moral codes and telling people to live by it is as ineffective for salvation as telling a helpless sheep that has gone astray (sinned) or has fallen into a pit (judgment): 

"Don't go astray or fall into a pit."

The sheep has already gone astray and/or fallen inside a pit.  The erring sheep (sinner) does not need more lessons on morals or more preaching of dos and don'ts that he wants to but is helpless to obey in his lost and fallen state. What he needs is the Good Shepherd to save him from his sins and the pit of judgment, provide his needs so he does not want, lead him on the path of righteousness and restore his soul- none of which the sheep can achieve by hearing preaching on law-keeping or human striving at attaining good morals. What he needs is the message of Christ: Grace- undeserved, unearned, unmerited favour. See the message of Christ in Romans 3:

"26...for He himself is fair and just, and He makes sinners right in His sight when they believe in Jesus. 27 Can we boast, then, that we have done anything to be accepted by God? No, because our acquittal is not based on obeying the law. It is based on faith. 28 So we are made right with God through faith and not by obeying the law."

This is right believing. And Christ does not just leave us to continue to wallow in sins after we are made right with God. Titus 2:14 says of Him-

"He gave His life to free us from every kind of sin, to cleanse us, and to make us His very own people, totally committed to doing good deeds."

When the believing is right, right living will follow. The one who depends on himself and his non-existent ability to keep the law will fail because "the arm of flesh will fail." The law is not of faith. Depending on human effort at keeping the law is being faithless. But no one will have to tell the one who is believing right- having Christ as our righteousness- to live right. No sin is too big for our Saviour to save us from. We GET TO live right because "it is no longer I who live but Christ lives in me." This is the message of Christ: Righteousness by faith.

Jesus never told Zacchaeus the tax collector: "You'd better stop serving the Romans and cheating your people or else." Before Zacchaeus met Christ, his entire community ostracised him and told him what he was doing was bad yet he did not change his ways. But after his one encounter with Jesus, Zaccheaus was transformed so much that he gave back what he stole when no one asked and became generous to boot. No one had to preach to him morals about not cheating or tell him about giving to the poor.

Christ never told the Samaritan woman at the well who had had five husbands and was living in adultery with a sixth man: "You'd better stop committing adultery or else God will punish you." Christ even complimented her for her coded response about having no husband. He offered her living water- He saw her thirst for Salvation where many saw her immorality. No word of condemnation or how great a sinner she was from our Saviour. Yet after her encounter with Christ, the woman became one of the first evangelists, telling her whole village about Jesus.

Christ never told the woman that was caught in adultery and was about to be stoned to death: "How could you! Now you have to go and stop sinning, sow seed and promise to keep the law or else God will punish you." Nothing the woman did could have saved her from the death that she deserved, just as no amount of preaching or adhering to moral codes can save anybody from judgment today. But Christ saved her from the judgment that she very much deserved. He died her death.

Believer, Romans 5:9 says of God: "And there is still much more to say of His unfailing love for us! For through the blood of Jesus we have heard the powerful declaration, “You are now righteous in My sight.” And because of the sacrifice of Jesus, you will never experience the wrath of God."

Believer, only because of the sacrifice of Jesus are we righteous in God's sight and do we get to escape His wrath. But false teachers will tell you that it is by human striving at keeping the law. Adding law-keeping to the story of our salvation is the way to get cut off from Christ and this is smack where Satan wants everyone to be:

"For if you are trying to make yourselves right with God by keeping the law you have been cut off from Christ! You have fallen away from God's grace." Galatians 5:4.

No wonder Satan and his agents in many churches are constantly preaching the "good thing" of law-keeping as the means of attaining godliness. They know Romans 6:14 - "For sin shall not have dominion over you for you are not under law but under Grace" - and are actively preaching the law in order to keep many under sin's dominion, after all, what is bad in keeping the law? But the letter kills.

Now that such false preachers see that God is opening the eyes of His people to see Grace, they are subtly trying to revise their message to include Grace. Such say: "Yes we are saved by Grace but we still have to obey the Law as a guiding principle for morality after we are saved." Believer, beware of dogs! Their horrid mixture of Law and Grace is the "neither cold nor hot" that Christ spoke of in Revelation 3. The law - for whatever reason one is under it- is not of faith.

See Paul's typology of Hagar and Sarah as the two covenants of Law and Grace in Galatians 4. Sarah (Grace) did not need Hagar (Law) to raise Isaac (the church- you and I in Christ.) Cast out the bond woman and her son! Child of God, by Grace, we reject any attempt by Satanic ministers to introduce Hagar (Law) as our nanny or as our whatever! Grace is sufficient for us.

No surprise that Satan, through his agents behind many pulpits, is constantly attacking any message that is built on sinners receiving God's abundance of Grace and His gift of righteousness to us in Christ. He knows that this is how we get to live in triumph over sin and death:

"For the sin of this one man, Adam, caused death to rule over many. But even greater is God’s wonderful grace and His gift of righteousness, for all who receive it will live in triumph over sin and death through this one Man, Jesus Christ." Romans 5:17.

When the believing is right, right living will follow. When Christ lives in you, no one will have to tell you not to covet, murder or fornicate because "God will continually revitalize you, implanting within you the passion to do what pleases Him." Philippians 2:13.

 We have the Lord as our Shepherd. How can we want for living a life of moral excellence when "it is no longer I that live but Christ lives in me?" Never trust yourself. Trust in the Lord with all your heart and lean not on your own understanding. This is the crux of the gospel of Christ:

RIGHTEOUSNESS BY FAITH.