As you can see, Madhuri, even those Christians who do not believe in the Trinity as defined by the Nicene Creed do not have the same reasons for rejecting it, and do not have the same understanding as to the nature of God or the relationship between the Father, Son and Holy Ghost. So far, you have heard from a Pentacostal Oneness Christian, a Jehovah's Witness and a Latter-day Saint, all of whom reject the Trinity, but for different reasons, and none of whom agree with each other as to what the truth really is.
From the LDS standpoint, the Father, Son and Holy Ghost truly are "one," but they are not "one" in substance. This is our primary disagreement with the Creeds. The Creeds are often said (by those who accept them) as being "summaries" of biblical information. We Latter-day Saints disagree. We see them not as summaries but of expansions and extrapolations. Where does it say that He is three persons in one being? The answer is that it doesn't. That's what the Creeds say He is, but it's not what the Bible says. The Bible says only that God is "one." It implies (in John 17) the way in which the Father and the Son are "one" but it never, ever even suggests that they are both part of a single substance. Nowhere does it say that. It says simply that they are "one."
It always amazes me how traditional Christianity can take a word such as "image" and completely redefine the word as it applies to man's relationship to God. "Image" is, by definition, the representation of physical qualities. Period. It has no alternate definitions. Traditional Christians, however, feel completely comfortable insisting that man is created in the image of a define substance which they believe to have no physical image.
Unlike the word "image," the word "one" does have multiple meanings, one of which is "united." And yet, when it comes to the word "one," they will insist that it must be understood to mean a numerical unit, a single "substance," instead of granting that it is much more reasonable, not to mentional scripturally consistent, to understand it as meaning "united."
Consider the following verses:
Exodus 24:3 ...and all the people answered with one voice, and said, All the words which the LORD hath said will we do.
Acts 4:32 And the multitude of them that believed were of one heart and of one soul...
Romans 15:6 That ye may with one mind and one mouth glorify God, even the Father of our Lord Jesus Christ.
In each of these verses, we can see that the one "one" is used to denote unity, not an actual number of units. The Latter-day Saints believe that the "oneness" of the Father, Son, and Holy Ghost is not of substance, but of absolute and perfect unity of mind, purpose, power and intent.
The purpose of the Creeds is to reconcile the problem of how three divine Persons can be one God. The way they (the Creeds) accomplish this is with two contradictory statements:
So the Father is God, the Son is God, and the Holy Spirit is God;
And yet they are not three Gods, but one God.
Trinitarian Christians believe these two statements, despite the fact that they cannot even begin to explain the logic of how both could be true. The Latter-day Saint understanding of the "oneness" of God is biblical, easily explainable, and internally consistent.