And after this manner shall ye baptize in my name; for behold, verily I say unto you, that the Father, and the Son, and the Holy Ghost are one; and I am in the Father, and the Father in me, and the Father and I are one.3 Nephi 11:27
But I thought we didn’t believe in the Trinity! We don’t. The Guide to the Scriptures says,
These three persons are one in perfect unity and harmony of purpose and doctrine.God, Godhead
They’re not the same person. They just are in unity.
We worship one God in Trinity, and Trinity in Unity, neither confounding the persons, nor dividing the substance. For there is one person of the Father, another of the Son, and another of the Holy Ghost. But the Godhead of the Father, Son, and Holy Ghost, is all one; the glory equal, the majesty coeternal. Such as the Father is, such is the Son, and such is the Holy Ghost. The Father uncreate, the Son uncreate, and the Holy Ghost uncreate. The Father incomprehensible, the Son incomprehensible, and the Holy Ghost incomprehensible. The Father eternal, the Son eternal, and the Holy Ghost eternal. And yet there are not three eternals, but one eternal. As also there are not three incomprehensibles, nor three uncreated; but one uncreated, and one incomprehensible. So likewise the Father is Almighty, the Son Almighty, and the Holy Ghost Almighty; and yet there are not three Almighties, but one Almighty. So the Father is God, the Son is God, and the Holy Ghost is God, and yet there are not three Gods but one God.Elder James E. Talmage, The Articles of Faith
They are very similar in all aspects, but they aren’t the same person.