1st Article of Faith

The first Article of Faith states, "We believe in God, the Eternal Father, and in His Son, Jesus Christ, and in the Holy Ghost." Source

Many do not consider LDS members to be Christian because we don't believe in the Trinity. If you are speaking of one entity manifested as God the Father, Jesus Christ, and the Holy Ghost, then no we don't beleive in the Trinity. If you are speaking of three entities forming a Godhood that work operate united in heart, might, mind, and strength that they work like one God then yes we do believe.

God the Father
We believe in God the Father as the father of our spirits (Malachi 2:10). He loves us. His only desire is that we gain immortality and eternal life (Moses 1:39).

Jesus Christ
I believe that people confuse Christ with God the Father because Christ is often called the Father. If we accept a lose definition that the title Father is 'one who gives life,' then both God the Father and Jesus Christ can be considered our fathers.

Our father on earth gave us our mortal life. God the Father gave life to our spirits. Jesus Christ becomes our father as we accept His path to Eternal Life (Ether 3:14).

No one can say that LDS members do not consider Christ our Savior and that we're not Christians (2 Ne 25:23-26). We rejoice in Christ. We follow His commandments in faith. We know that our works alone cannot save us. We are saved by the grace of Christ which is available as we strive to be obedient to his commandments. We seek no other source for our salvation.

Holy Ghost
We believe in the Holy Ghost as a distinct entity from the Father and the Son. He is a "personage of spirit" (D&C 130:22).

The Holy Ghost serves many missions and purposes on the earth. Some of the most important are taught by the apostle John. In the absence of Christ's direct presence on the Earth, the Holy Ghost teaches us truth and the way of Christ. He reminds us of truth when needed to make correct choices (John 14:26). The Holy Ghost doesn't speak, he testifies of truth when it is heard (John 16:13).

Some describe the testimony of the Holy Ghost as a burning in the heart. For me, his testimony comes as a compelling pull of my attention and curiosity. Satan does try to counterfiet that testimony for me with thoughts that occupy my mind but they come in the spirit of anger, contempt, and pride.