Worship is human response to divine revelation. When ever and where ever the vision of the Lord was seen the immediate response of the one who saw it was one of falling at the feet and worshipping. If there is a desire in our hearts to worship Him, it is because we too have seen Him with the eyes of faith. One who has never seen Him could never worship Him.
Now, you ask me if a non-Christian can join in praise and worship as a Christian does. Well, Public worship is a time when the people of God gather together to worship their God. Usually in a Christian meeting where preaching and teaching is involved, all are allowed to join in. And naturally all our meetings begin with the worship of God. Then we invite non-Christians as observers even on a Sunday worship meeting. Some even come to observe the Holy Communion services. To ask them to join us after the praise and worship would not be practical in any way. On the other hand, some have come to know the Lord simply by attending a full fledged praise and worship meeting where there was no preaching of the Word was scheduled!
It is true that a non-Christian can not worship God because he is dead in spirit. But being present in a meeting where praise and worship is going on might give him an opportunity to come to know the living God. Please read what the Psalmist says. `And he hath put a new song in my mouth, even praise unto our God: Many shall see it, and fear, And shall trust in Jehovah` (Psa 40:3 ASV). Don`t you want your non-Christian friends to fear and trust in the Lord? The Psalmist says that when they see us praising God with a new song, many will fear and trust in the Lord! May that be so even in these days. To His name be glory. Amen.