Judaists and Muslims claim Moses and the godly before him worshipped a unitarian god. But Calvin-ists, alias consistent believers in the Holy Bible, assert that not just Moses (Exodus 3:2-16 cf. John 5:45f) but all prior Patriarchs from Adam to Job too worshipped only God Triune.
Calvin comments on Genesis 1:1-3 that "Moses has…Elohim, a noun of the plural number…. Moses afterwards subjoins that Elohim had spoken forth God’s Word; and that the Spirit of the Elohim rested upon the waters…. The Scripture…always recalls us to the Father, and His [Son or] Word, and Spirit….
"The power of the Spirit was necessary….. The mass… was rendered stable…by the secret efficacy of the Spirit…. The Spirit moved…over the waters…to prevent its speedy dissolution….
"Moses now, for the first time, introduces God in the act of speaking…the Word…. John [1:3] testifies that ‘without Him nothing was made’…. The world had been begun by the same efficacy of the Word by which it was completed…. Since by the Word of God things which were not, suddenly came in being — we ought…to infer the eternity of His essence…. All things have been created by Him…. He is the Wisdom dwelling in God, without Whom God could never be."
Too, in Genesis 1:26, God Triune – comments Calvin – "is about to undertake something great…. The [judaistic] Jews make themselves altogether ridiculous, in pretending that God held communication with the earth or with angels…. Christians therefore properly contend from this testimony [‘Come let Us make man!’], that there exists a plurality of Persons in the Godhead…. I acknowledge indeed that there is something in man [‘the image of God’] which refers to the Father and the Son and the Spirit."
Already at Adam’s creation, God anticipated even the very manner in which Christ would later breathe His Spirit into His elect Apostles. For even way back then, the Triune God (viz. the Father through His Word and Spirit) breathed into man the breath of life and man’s own logos or reason. Without such, there could have been no comm-uni-cation or comm-uni-on between God and even pre-fall man – and no prefall human worship of the Triune God.
Calvin comments on God’s creation work: "Six days were employed in the formation of the World…so that He might engage us in the consideration of His works. He had the same end in view in the appointment of His Own rest. For He set apart a day selected out of the remainder, for this special use….
"God claims for Himself the meditations [on His Word and the Spirit-ual praise and prayers]…of men on the seventh day. This is…the proper business of the whole life in which men should…exercise themselves…. Every seventh day has been selected especially for the purpose…, so that in all ages it might be held sacred….
"The Sabbath was a figure of this rest…. It was commanded to men, from the beginning, so that they might employ themselves in the worship of God. It is right that it should continue to the end of the World…..
"We have an equal necessity for the Sabbath with the ancient people, so that on one day we may be…the better prepared to learn and to testify our faith…. The hallowing of the Sabbath was prior to the [Mosaic] Law…. [It] seems to have had its origin from a well-known and received custom…. It is not credible that the observance of the Sabbath was omitted when God revealed the rite of sacrifice to the holy fathers." Cf. Genesis 3:15-21 & 4:2-4 & 8:20-22.