When else do you meet together with other people & break out in song? Hardly ever! Maybe we mumble through the national anthem with strangers at a ballgame, but it's just not the same. And no matter how many times I talk to my neighbor over the fence or over the lawn mower, we're never going to belt out a chorus together.
And yet, almost as soon as you walk into a Christian church, you find yourself singing.
Consider this quote from W.M. Clow:
"There is no forgiveness in this world, or in that which is to come, except through the cross of Christ. 'Through this man is preached unto you the forgiveness of sins.' The religions of paganism scarcely knew the word. ... The great faiths of the Buddhist and the Mohammedan give no place either to the need or the grace of reconciliation. The clearest proof of this is the simplest. It lies in the hymns of Christian worship. A Buddhist temple never resounds with a cry of praise. Mohammedan worshippers never sing. Their prayers are, at the highest, prayers of submission and of request. They seldom reach the gladder note of thanksgiving. They are never jubilant with the songs of the forgiven."
But when the church of Jesus Christ comes together, it's impossible to keep them from singing. That's what the free gift of grace to the undeserving will do. It loosens your tongue, it gladdens your heart. You celebrate. You sing.
You sing the songs of the forgiven.