The first vision of Joseph Smith represents to Latter-daySaints the beginning of the revelation of God to man in the final dispensation. Knowledge pertaining to the nature of God - his character, personality, divine attributes, powers, and purposes - have been known to latter-day prophets, and some of the knowledge obviously stands in contrast to what many in the Christian world would believe about God and about man's relationship to Deity.
1: The Trinity - An LDS Belief? (Godhead):
The answer to this question depends entirely on the inquirer's definition of "trinity". Webster's New Collegiate Dictionary defines the word trinity as "the unity of Father, Son, and Holy Spirit as three persons in one Godhead. The Random House College Dictionary adds a second alternative to this definition which allows also "the threefold personality of one Divine Being". Although Webster's definition would be considered a valid LDS description of the Godhead, the second Random House alternative would be considered by Latter-day Saints to be an apostate view.
Today, some people assert that a belief in a mysterious unknowable Trinitarian god is essential to a claim of Christianity even though this requirement is not biblical. At times they use Colossians 2:9 as a proof text to support their Trinitarian concept: "in him[Christ] dwelleth all the fullness of the Godhead bodily." Though this scripture could appear to vindicate the belief in the trinity, the Greek text does not justify this interpretation. The Greek word translated as Godhead in this verse is "theotes." This word actually means "divinity" and is translated as such in many modern Bible translations. Accurately translated, this verse should read "in Christ the fullness of divinity dwells in bodily form" {See New International Version}. Therefore, the qualities of Godhead are manifest to us in Christ but Christ is not God the Father.
It is important to note the word "trinity" does not appear anywhere in the King James Version nor any other reputable translation of the Bible. The present Trinitarian concept cannot be derived from an impartial reading of the Bible. Justification of this doctrine using citations of biblical verses is weak and inconclusive at best. The term Godhead, on the other hand, is an accepted biblical term {Acts 17:29; Rom1:20; Col. 2:9} and the preferred title in the LDS Church.{1} References to the Godhead as the trinity are found in LDS Church literature {2} but such usage clearly denotes a three-person Godhead and not a one-being concept.The latter concept of the trinity, now held by much of "mainstream Christianity", seems to have originated under the influence of the Greek and other oriental philosophies during the period of apostasy following the death of the apostles. {3} A study of Christianity prior to 325AD reveals that the LDS interpretation of the Godhead was then the prevailing belief. Church fathers such as Ignatius, Justin Martyr, Origen, Athanasius, and others argued that the Godhead consisted of separate Beings. {4} The first person to use the term trinity appears to have been Tertullian in about 200AD. He used the term to refer to ideas which mentioned three and one.
Over a century later, in 325AD, the Roman Emperor Constantine convened a delegation composed of about one-sixth of the bishops from throughout the Roman Empire. The stated purpose of the Council of Nicea as it was called, was to achieve unity among the factions that existed then. Three major groups with differing views regarding God's nature at length became two factions. The eastern (Arian) Christian view favored a three-God concept while the western (Roman) view favored one supreme God to whom all others were subordinated. Under extreme intimidation by the emperor, the Arian group was compelled to yield to the Roman view. Araus and the bishops and priests who opposed the Nicean Creed and the "one substance" terminology adopted by the council were exiled. Constantine, in order to ensure future unity, also commanded that the writings of these men be burned. {5}
The Nicean Creed stated that there was "one God and one Lord Jesus Christ the Son of God" who was "one substance with the Father." The Athanasian creed, which was an outgrowth of the Nicean Creed, typifies the modern "orthodox" concept of the trinity. It speaks of an "incomprehensible" God which is completely foreign to Christ's teachings. Jesus taught that "this life eternal that 'we' might . . . know the only true God, and Jesus Christ whom God had sent"{John 17:3; see also Jeremiah 31:34; John 8:19; 14:7-9, Hebrews 8:10-11, 1 John 2:3-4, and 1 John 3:1-2, 6; 5:20}
Thus, the accepted Trinitarian concept of deity is the result of a compromise achieved without the benefit of apostles, prophets, or revelation and arrived at only when extreme pressure was exerted by a then pagan emperor. The true concept of God is not that of an "unknown" or unknowable God {Acts 17:23} but one whose offspring we are {Acts 17:28-29} and in whose image we were created {Gen 1:26-27}. Our Heavenly Father loves us and wants us to know him and become like him {Matt 5:48; John 3:1-2}
Conclusion - The trinity that "mainstream Christianity" follows today of the three in one concept is not of God and never was. It doesn't follow scriptural references in the Bible and was not brought forth through apostles or prophets and therefore is doctrines of men. The LDS get hammered with accusations of following the doctrines of men but in reality those that judge do not look in their own scriptures to find out if the doctrine preached is actually truth.
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Footnotes:
{1} History of the Church, 6:473; Lectures on Faith, Lecture 5; pp 58-59
{2} Articles of Faith, pp. 39-41; Journal of Discourses, 6:95; History of the Church, vol1, Intro., pp 80-81
{3} History of the Churh, vol 1, Intro. pp 82-87
{4} see J.D.N Kelly, Early Christian Doctrines, pp. 93, 96, 129, 233
{5} James K. and Rose Seastrand, Journey to Eternal Life and istratios Along the Way, p 132; History of the Church vol 1, Intro., pp 79-90