Ok, for this this explanation I’m going to be explain the views/beliefs/teachings of the Church of Jesus Christ of Latter-day Saints. All quotes are from books considered by LDS Christians to be scriptures, marking non-Bible ones with * to be super transparent.
Point 1) ““We believe in God, the Eternal Father, and in His Son, Jesus Christ, and in the Holy Ghost.” (Articles of Faith 1:1) The Father, Son, and Spirit are all God and are three divine different persons. Christ doesn’t pray to Himself and the voice from Heaven saying “this is my beloved Son in whom I’m well pleased” (Mathew 3:17) is not an act of ventriloquism. It isn’t one person taking on different roles (modalism), but three different persons. At some points in scripture God is used in plural (example: “And God said, Let us make man in our image” Gen 1:26). Classical Trinitarians agree on this.
Point 2) There is ONE God. Three persons, but ONE God. Classical Trinitarians agree on this as well. Quick sample list of scripture verses saying this:
- I and my Father are
one,
John 10:30.
- that they might know thee the only true
God,
John 17:3.
- to us there is but
one God,
1 Cor. 8:6.
- they are
one God,
Mosiah 15:4 * (
3 Ne. 11:36; *
D&C 20:28*).
- sing … unto the
Father, and unto the
Son, and unto the
Holy Ghost,
Morm. 7:7. *
Point 3) “Monotheism” is defined as the worship of one God. While Muslims and others may throw those tired “three persons isn’t one God!” arguments, frankly, I’d rather skip discussing those tired arguments we’ve all heard a million time. The Father, Son, and Spirit are ONE God. To honor the Father is to honor the Son, to yield to the Spirit is to yield to the Son, etc. You can’t choose to go “well, I just want to follow Christ and disobey the Father!” – such is downright silly. They are one and both LDS Christian and Classical Trinitarians are monotheism, even if it’s different than monotheism in Islam.
Point 4) How three person are one God: this is where the difference between LDS Christian beliefs and Athanasian Christian beliefs is. For LDS Christians, God is one via unity—“That they all may be
one; as thou, Father, art in me” John 17:21,
D&C 35:2*. That’s it. There’s no Athanasian Creed stating saying that they are one througha substance/essence (“…but by assumption of the Manhood into God. One altogether; not by confusion of Substance [Essence]; but by unity of Person. “
Athanasian Creed - Wikipedia). No “three persons but one being” with long confusing explanations as what’s a “being” versus what’s a “person”, while trying to stay away form modalism. Just three different persons in ONE God via unity.
Point 4b) How does the above impact day-to-day living as a disciple of Christ: honestly, not much. Not to downplay the importance of academic theology, but there isn’t much day-to-day impact here. Each having a relationship with Christ, whom majesty we don’t much understand, trying to follow Him. I don't remotely find such to be a reason for anyone to point and scream "you're not really a Christian because you can't be because your salvation is dependent on your ability to pass this theology test!!". Such is downright silly actually. Yes theology is important, but it's discipleship that makes one a Christian (Act 11:20).