WCF 21

God has instituted acceptable way of worshiping him, and so limited worship by his own revealed will, that he may not be worshiped according to human imaginations or devisings, …or any other way not commanded in Holy Scripture….

Prayer with thanksgiving is a special part of religious worship and is required by God of all people. In order that prayer may be accepted, it is to be made in the name of the Son, by the help of his Spirit, and according to his will….

The [other] elements of the ordinary religious worship of God are:

  • the reading of the Scriptures with reverence;
  • the sound preaching and conscientious hearing of the Word in obedience to God, with understanding, faith, and reverence;
  • the singing of psalms with grace in the heart; and
  • and the proper administration and worthy receiving of the sacraments instituted by Christ.

Also, on special occasions and at appropriate times, there are other elements of worship, namely,

  • religious oaths,
  • vows,
  • solemn fasts, and
  • thanksgivings.

These are to be used in a holy and devout manner.

from the Westminster Confession of Faith, 1646

Chapter 21