Amen.
"...In exposing the idolatrous nature of the Mass, Knox stresses that all religious ceremonies and institutions must have clear biblical warrant, if they are to be admitted as valid expressions of worship. All worship invented by man is idolatry. Knox demonstrates that the Mass is a human invention; and, therefore, the Mass is idolatrous. The entire discussion turns upon Knox's defence of the scriptural law of worship..."
Idolatry is worshiping false objects, objects other than God. The Divine Liturgy (Holy Mass) is entrely focused on worshiping the Triune God. Is the manner of worship now made idolatrous becase John Knox says it is? If so, then the muscial instruments in the Presbyterian churches are idolatrous innovations as well, for any kind of instrumental music was originally banned by the Reformers. And so are microphones and visual aides, because none fo these are mentioned in the Bible.
I think it would be good for the Protestants to look for logs in their own eyes before they busy themselves finiding thorns in other churches. For starters, they can show us where does the bible say that divorce is somehting Christians can exercise freely? Does it ever occur to the Protestants that perhaps they do many things that are not scripturally sound?