We are Confessionally Reformed. That is, we maintain a strict adherence to the Westminster Confession of Faith (1646/7). Such a Reformed Confession does not add to the Word of God, but it merely mirrors and systematizes what the Bible teaches concerning the Bible, God, man, Salvation, Christ, the Church, and other core beliefs.
Because we are confessional, we endeavour to worship the one true and living God strictly according to the Scriptures. For, it must be admitted, that only a holy God knows how a holy God must be worshipped. This is called: The Regulative Principle of Worship.
Therefore, we must have a Biblical warrant for every element of worship. Consequently, we read the Word (Acts 13:15), we preach the Word (2 Timothy 4:2), we pray in the Name of the Word (John 14:14), and we sing unaccompanied the Word of Christ (the Psalms) (Colossians 3:16), upon the only New Testament holy day, the Lord's Day (Acts 20:7).
More information: The Scriptural Regulative Principle of Worship - The Presbytery of the United States | The Free Church of Scotland (Continuing)