"All authority has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you". Matthew 28: 18 - 20.
Ministries that fight the acceptance of certain sins in public life are seeking to teach the nations to observe what Christ has commanded. In nations like ours with a Christian heritage, where many people still label themselves "Christian" and have been baptised, this is an even more legitimate goal. We are not just to disciple individuals. Our efforts are also meant to have an impact upon whole nations.
It is also a meaningful activity to promote godly values because these are loving. If we love people, we will not want them to suffer the awful affects of sins like abortion, promiscuity, homosexuality, or divorce. When these sins are common and acceptable, people become involved in them almost as a matter of course. In contrast, if godly patterns of relationships are normative people tend to follow these.
Yet there is also a danger as Christians publicly argue against certain behaviours. It can seem like we are saying that we are not sinners and others are. If the moral messages are not combined with the gospel this will be the message that is conveyed. This is damaging.
Paul preached a different message . . .
Here is a trustworthy saying that deserves full acceptance: Christ Jesus came into the world to save sinners—of whom I am the worst. But for that very reason I was shown mercy so that in me, the worst of sinners, Christ Jesus might display his unlimited patience as an example for those who would believe on him and receive eternal life. 1 Timothy 1:15 - 16.
As we seek to love the nations, and to disciple them so that they obey Christ, it is imperative that we do not convey false messages about the gospel. The gospel teaches us that we are the worst of sinners - every single one of us. "I am the worst of sinners" needs to be one of our primary messages. Christ has transformed us, and that is why we love others enough to care what is happening in our nations.