United Church of Christ membership decline

The United Church of Christ (UCC) has expereinced a decline in membership and weekly worship attendance. In the last 10 years, this denomination has experienced a 230,000 member drop or minus 15%. Their weekly worship attendance is showing about the same decline. Some UCCs have been able to maintain their membership and worship attendance. However, most have experienced a decline.
Most so-called mainline denominations have experienced similar declines. Why? I am of the opinion that there are several forces at work in these denominations, which are primarily European American.
First, I think the demographics are changing. Young European Americans on their faith journey are drawn to a more lively and contemporary religious service. Mega churches are a big draw.
Second, for the younger generation, contemporary, feel good, "Jesus Lite" music is appealing. The old hymns and gospels do not inspire the younger generation.
Third, the mainline denominations do not evangelize effectively. Can you imagine inviting someone to your mainline denomination to hear a sermon of the merits of supporting Bill Clinton. I heard a sermon at a UCC on this topic when Bill Clinton was being impeached.
Fourth, most mainline denomination, including UCC have been moving more to a social gospel. There is not much inspiration value in preaching about Global Warming, Voting Rights Act, or the value of Affirmative Action. Oh yes, I have heard sermons on similar topic at various UCCs.
There are other issues that have impacted mainline denominations and the drop in membership. This being said, I enjoy my association with and membership at UCC. Because, a long time ago I belonged to a highly critical fundamentalist church and I was robbed of my faith. And, a UCC pastor helped restore my faith in God. Praise the Lord.