Nothing was more important to John Calvin than the pure worship of God in spirit and in truth. Several Biblical texts played a role in Calvin’s development of his doctrine of the worship of God.

You shall have no other gods before Me.- Exodus 20:3

Calvin understood that concern of the First Commandment was worship. In it God, “enjoins that He alone should be worshipped, and requires a worship free from all superstitions.— God, therefore calls for the affections of the hear that He alone may be spiritually worshipped.…thence we arrive at the distinction between true religion and false superstitions; for since God has prescribed to us how He would be worshipped by us, whenever we turn away in the smallest degree from this rule, we make to ourselves other gods, and degrade Him from His right place.” — CALVIN’S COMMENTARIES, Vol. II, p. 418, 419