Great song and one of the mainstays at Calvary Chapel. Anyone who has sung this side by side with 20,000 brethren has met with a very powerful experience.
http://www.youtube.com/watch?v=ENtL_li4GbE
The author:
http://www.beholdthebeast.com/one_more_time.htm#91
Not to throw cold water on matters, but it's also important to keep from being driven by our emotions, and understand an emotional experience in this context:
Jeremiah 17:9 The heart [is] deceitful above all [things], and desperately wicked: who can know it?