Trinity - the importance and necessity

A key aspect of the essence of God is relationship. Without the relationship between Father, Son, and Spirit there is no God (or love). The oneness of God is a oneness of relationship; a union of three. Even though each of the three persons of the Godhead is God, they are God together and not God separately or independently and individually without or outside of relationship.

None of the persons of the Godhead stand alone, independent of each other by virtue of the fact that to be fully the God He is, He must be God in relationship, making all three persons necessary for "Godness" to exist.

When the Bible says that God is love it is because he is relationship. And not just any kind of relationship but one defined by love i.e. the giving and receiving of glory/value/worth/honor. A relationship in which each is equally and mutually valued/loved/honored by the other.

Because the Son issues forth from the Father and the Spirit issues forth from the Father and the Son they are all God. So in this sense everything issues forth from only one God as Father, yet God cannot be Father without the Son and the relationship between the Father and the Son is bound together and expressed in, by and through the Spirit, who is love. There is no relationship between the Father and the Son without the Spirit. 

God is Spirit and God is Love. And He is all these because He is relationship. And because He is relationship He is all these.

For a much fuller discussion of this click here

For a discussion on the source of love click here

For a discussion on the "dependence" of God click here.