Corporate worship: a divine work, a saving work of God.
It is the Holy Spirit who purifies our worship by his continual work of sanctification. As the Spirit purifies the worshippers, the worship is made pure. When we worship, having our minds enlightened by the Spirit, our lives cleansed by the Spirit, our wills moved by the Spirit, and our hearts warmed by the Spirit, then our worship is transformed from being merely a human work into being a divine work.
Hughes Oliphant Old, Worship, Westminster John Knox Press, 2002, pg 6.