Within the Christian church there are two basic forms of worship: the regulative principle of worship (RPW) and the normative principle of worship (NPW). Basically the regulative principle allows only that which is explicitly mentioned in Scripture. And the normative principle allows anything which isn't explicitly forbidden by Scripture. In many RPW churches you will find exclusive psalmody (EP). With exclusive pslamody the Psalms contained in Scripture are the sole form of music permitted in worship. They are sung by the congregation and no musical accompaniment is permitted.
I favor the normative principle, it gives us the freedom to praise God using all of our talents and utilizing the best hymns and sacred music of the past. I find the regulative principle to be overly restrictive and not supported by Scripture. We have examples of people praising God using instruments in Scripture. I cannot imagine that when we perform Bach's sacred cantatas we are somehow sinning against God and that the music is not true worship! There is lots of legalistic thinking in proponents of EP so be careful if you run into them.
Here is a good article which discusses these issues.
