Why is singing so important for Christians?

From Gospel Translations

Is it true that Christianity is unique in the fact that it is a singing and rejoicing faith?

Absolutely. I don't think there are any other religions that sing like Christians sing. Christians really make music over their faith.

Even the sheer radio reality of Christian contemporary music is an interesting phenomenon. It has many pitfalls because of, perhaps, the way that theology is dumbed down in it or the way it is infected with an entertainment mindset; but the sheer existence of Christians who are always looking for ways to make melody about their faith--finding inspiring tunes growing out of their convictions about God and Christ and forgiveness and eternal life--I think that is an amazing and unique thing. I don't think there are any other faiths in the world that come close.

In fact some faiths, like Islam, don't even believe in singing. But what kind of faith could say that the human heart, with its readiness to make melody over almost everything it enjoys, should not do that over the most important reality in the universe? That's a really strange religion, I think.

The fact that Christianity is a singing religion bears witness, not only to the way we're wired as human beings, but to the kind of God we have: namely, a God who is one day, according to Zephaniah 3:17, going to sing over us. He is going to lead a choir and celebrate the fact that we are his. And we're going to join in singing that he is ours, because God is so valuable and so beautiful and so multi-faceted in his perfections that to leave out the emotional component--and not let it spill over in poetry and song--would be to leave out a key element in worship.

I really don't have a lot of patience, frankly, even with Christians who want to put a lid on music and singing, or put it back five centuries, or limit it to one kind of instrument, or take away all instrumental music and just let it be voice. I think that all of that is hopelessly defeatist, because we humans have explosive souls; and the reason we do is because God is explosively beautiful and great and glorious. He is going to call out from us song and music of every kind, and we might as well just let it out and try and bring it into its deep, powerful significance with truth.

That's the crucial thing: govern our music-making with true biblical doctrine.