The REGULATIVE PRINCIPLE

"Whatsoever God has not commanded in His Word for His worship is not allowable in divine Worship."

This was in keeping with John Knox's dictum.
"All worshipping, honouring, or other service invented by the brain of man in the religion of God, without His own express command is idolatry."

That principle is, to put it simply, 'Scripture Alone'.

This principle is re-stated in The Nonconformist's Catechism (by Samuel Palmer) of 1741;-
36. Q. Is nothing to be required in the worship of God but what is commanded in Scripture?
        A. Nothing but what is either expressly commanded, or necessarily implied in a command.

The Scriptural Regulative Principle was not invented by the Reformers,.
"We are enjoined by Christ Himself to put no faith in human doctrines, but in those declared by the prophets and taught by Himself." Justin Martyr
"It is a manifest falling away from the faith and a mark of presumption, either to omit anything in Scripture, or introduce anything not in Scripture." Basil the Great
"We deny not those things which are written, we refuse those which are not written." Jerome
Also, there are similar statements by Lactantius, Tertullian and others.

This was the principle laid down for the order of worship among the Israelites,
"See that you make it according to the pattern that was shown to you on the mountain." Ex.25;40; and this was repeated (for our guidance) in Acts.7;44. The manner of this presentation is not merely historic, it implies that, as a spiritual application, it is one of those parts of the Old Covenant which are translated into the New Covenant. This is one of the principles which Bible obeying, New Testament, Christians have used since the Gospel Age was introduced.

The apostle Paul, and Apollos too, encouraged the Assembly, Congregation, Gathering, at Corinth 'not to go above that which was written'. 1Cor.4;6