I remember someone asking me when I was a teen, "What is worship?" What kind of question is that? Everyone knew what worship was. But if everyone knows what worship is, then why did I have such trouble trying to tell my friend what worship is? I described things that we did in worship, but it was hard to tell this person precisely what worship is. An adult standing nearby said, "Worship is paying homage to God." Well, that cleared everything up! What did that mean?
One of the difficulties with worship is that the Bible never precisely defines it. There are descriptions of what happens in worship, accounts of people that responded to God in worship, and accounts of instructions from God concerning worship furnishings and the meaning behind them. However, there is no "definition" of worship.
Perhaps the reason there is not a definition of worship in scripture has to do with the danger of losing something really important and integral to worship in an over-analysis of it. Since God's ways are higher than our ways and his thoughts are higher than our thoughts, and since God is the infinitely powerful and wise creator who condescended to our level so that we can know him, there will always be a sense of mystery to worship.
About all we can do is learn from the various descriptions, accounts, instructions, and stories related to worship in scripture and learn from them. Worship is almost always a response to the God who acts on behalf of his people, whether it is creation or redemption. For instance, when God delivered Israel from slavery, the first thing Israel did after the crossing of the sea is sing the song that is now commonly known as the Song of the Sea in Exodus 15. God called Israel, and Israel began to call on God. So worship is basically a heart-felt response to the living God.
God is not an idol, nor is God merely an idea. God is the living God who acts on our behalf. Sometimes worship may lead a visitor to wonder whether some Christians are functional deists, believing that God is not engaged with his creation, but only watches it.
God did not merely act when he created the world. The stories we recount of God's mighty acts remind us that God is interested and intensely involved with his creation. The cross reminds us that God intimately engages the world. The book of Revelation reminds us that God is behind world events.
Worship, then, should not merely recount that God did for ancient people, but should also recount what God does for his people today right here and right now. Since God is the living God, and since God is not merely a watcher of men, we worship a God who had come near and is still near through Christ! Songs, prayers, commemorations, etc. should reflect not only that our God acted long ago, but that he is still here with us. Truly, worship will be a continual response to the living God.