We clap our hands because Psalm 47:1 says, "O clap your hands, all ye people."
We sing and play music because Ephesians 5:19 says to worship "in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord," and Psalm 150 says to praise God with musical instruments.
We worship with a joyful noise because Psalm 66:1 says, "Make a joyful noise unto God, all ye lands."
We pray aloud because the early church "lifted up their voice to God with one accord" in prayer (Acts 4:24).
We dance in the Spirit because Psalm 149:3 says, "Let them praise his name in the dance."
We include testimonies, teaching, preaching, and spiritual gifts because I Corinthians 14:26 says, "Whenever you come together, each of you has a psalm, has a teaching, has a tongue, has a revelation, has an interpretation" (NKJV).