Reading further in the Lifeway article on the role of music in church, it notes reasons many in today’s churches don’t sing. Most are the fault of the church’s worship leader.
Knowing what to sing
The first is that folks don’t know the music. Our church used to sing a lot of new choruses. But then we’ve got several Christian radio stations. When I lived in Massachusetts, there were none. We didn’t hear many new choruses. There, it would take several times singing to get the words down. If you have a choir, teach the chorus to them and let them support the congregation at first.
Today, our church has the opposite problem. The new worship pastor likes to use hymns as well. The old folks love it, but the young people didn’t grow up with them, and it’s both foreign words and strange music. Again, having a choir helps support the singing.
It’s too hard
The second reason is the range. A lot of choruses are sung in the same key they are played on the radio. By a Tenor. Today’s choruses tend to be written for high voices, but most of the congregation are middle to low voices, and a fairly small vocal range. When the song exceeds their ability to sing it, they will quit singing.
Sounds like a concert
The third reason is that we present the music as a concert. Many churches don’t have choirs, but only a worship band. Often the music is loud, like a concert, in a warehouse situation, and even if the person did sing, they couldn’t hear the other voices around them. It sounds like they are singing alone, and if they feel they don’t have a good voice, they’re not comfortable singing alone in public.
The solution would be to lower the volume of the instruments, or sing a capella some. Sound management in the room (dampening, amplifying congregation sound, etc) can also help.
Conclusion
When people don’t sing, it’s because the music leader is picking music the congregation doesn’t know, or because they feel like they’re singing alone, or they don’t see how their singing adds to the sound, there being so much else from the band.
To improve congregational singing, the simplest is to have a choir, and to tone down the instruments some.