Paul stresses the fact that God responded to the rejection of him by his creatures and did so in a certain way. Because they rejected him by engaging in idolatry, he gave them up to immoral practices, including homosexuality.
While it is true that some people (philosophers and others) in the ancient world disapproved of such practices, it is the case that Paul mentions similar lifestyles were common among Gentile Christians before they were converted (1 Cor. 6:9-11).
But immorality, says Paul, was not the only practice that God gave people up to engaging in. He provides a list of some of their activities, and when we read verses 28-31 we will see that several horrid and ugly actions are included. It might surprise us to find gossiping in the list. Sadly, Paul's list is not only a description of some in the ancient world, it is also a description of some today. The fact is, sin has a wide variety of expressions and practices.
And Paul then wrote something that we might find startling. We might assume that people did this wrong behaviour out of ignorance, but Paul says that it was otherwise (v. 32). They approved of such behaviour even although they knew God disapproved of it. I think Paul is referring to their sense of right and wrong and their awareness that wrong actions deserve to be punished. Nevertheless, they persisted in doing them. It is the same today. This attitude, of course, means that saying something is wrong to many people will have no effect whatsoever on them.
We should see the connection Paul makes between rejection of God and the range of sins that will be practised. The more he is rejected, the greater will be the diversity and volume of sin. Rejection of the authority of God is the defining mark of our society, and if it continues to reject him then who knows what kinds of sins will be tolerated, even advocated?
According to Paul, how does one know if one lives in a society that is under the wrath of God? Sometimes we may imagine that the wrath of God, when it is displayed, will be like a ferocious gale sweeping away everything in its path. Of course, his wrath could be revealed in such a way. Yet Paul says that wrath is shown in the fact that God gives people up to their own choices. He takes away restraining grace and that is an expression of his wrath.
So we should be amazed that in the middle of sin-saturated, rebellious societies the most sinful of people come to faith in Jesus. In addition to being amazed, we should be witnessing to the grace of the God who forgives all kinds of sinners.