It’s biblical. The New Testament commands Christians to sing together, even to address one another in song (Eph. 5:19; Col. 3:16).
It’s neglected. In many churches, the music can actually discourage singing, whether because so much of it is performed, or the accompaniment is so loud, or the music is hard to sing. We emphasize congregational singing because so many churches seem to neglect it.
It’s simple. Congregational singing doesn’t need amplification, a full band, or even, strictly speaking, any accompaniment. It can work in a church of 30 or 3000. It can even work when the power goes out.
It’s transferable. Because congregational singing is simple, it’s transferable. A church plant meeting in a home can sing congregationally. A church in Thailand or Madagascar or Brazil can sing congregationally. Which means, incidentally, that international visitors to the United States often feel more comfortable entering a church that promotes congregational singing. After all, they often come from settings where the music is less professionalized and performance-driven.
It’s unique. You can hear Christians perform music at concerts. You can buy the latest praise music on iTunes. But you can’t typically hear dozens or hundreds or thousands of saints all lifting up their voices together in praise to their Savior anywhere else, this side of heaven, except the local church.
You can take it home. Music which is conducive to congregational singing tends to be similarly conducive to singing around the family dinner table.