Barry Bickmore writes that the Bible contains four propositions about God that every Christian denomination must reckon with in its theology.
(1) First, is that the Bible contains several strongly monotheistic statements. When Moses says, “Hear, O Israel: The Lord our God is one Lord” (Deuteronomy 6:4), he means, as the Muslims say, “There is no God but God.” This view also finds support in God’s statement to Isaiah that, “I am he: before me there was no God formed, neither shall there be after me.” (Isaiah 43:10) This tradition is continued in the New Testament as, for example, when Jesus prayed to the Father he said, “And this is life eternal: that they might know thee the only true God, and Jesus Christ whom thou has sent.” (John 17:3)
(2) Second, there is a person called the Father, who is identified as God. The example of Christ’s “high-priestly prayer,” quoted in part above, should be ample evidence of this fact.
(3) Third, there is a person called the Son in the New Testament, namely Jesus Christ, who is called God. Clearly identifying Jesus as “the Word,” John wrote, “In the beginning was the Word, and the Word was with God, and the Word was God.” (John 1:1) Here Jesus is presented as God, but also as distinct from the Father, hence the phrase, “and the Word was with God.” There are numerous other examples of this throughout the New Testament.
(4) Fourth, there is a person called the Holy Spirit who is identified as God. That the Holy Spirit is God is shown by Peter’s accusation of Ananias, “Why hath Satan filled thine heart to lie to the Holy Ghost” … Thou has not lied unto men, but unto God.“ (Acts 5:3-4) The New Testament also teaches that the Holy Spirit is a person, distinct from the Father and Son: ”But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you." (John 14:26; see also Acts 13:2)
Naturally, these propositions present a problem. Are there three Gods or one? For Latter-day Saints, it is acceptable to say both that there is one God, and that there is a plurality of Gods, depending on the context. Quoting Joseph Smith, “I have always declared [that] … these three constitute three distinct personages and three Gods.” (Joseph Smith, in TPJS 370). Yet in the Book of Mormon, the prophet Nephi preached the way to salvation, or “doctrine of Christ” was the “only and true doctrine of the Father, and of the Son, and of the Holy Ghost, which is one God, without end.” (2 Nephi 31:211) What is the nature of this “oneness”? In Jesus’ great Intercessory Prayer (see John 17), He asked that His disciples would be made one in Him as He was one in the Father. [Barry Robert Bickmore, Restoring the Ancient Church: Joseph Smith & Early Christianity, pp. 77-78]