As Latter-day Saints, one core doctrine is a belief in God the Father, His Son Jesus Christ and the Holy Ghost.  As is taught in the Bible, we believe that these three are distinct, separate persons.  God the Father and Jesus Christ have physical bodies while the Holy Ghost is a personage of Spirit.  God the Father is the father of our spirits establishing the doctrine that all people on earth are literally spiritual brothers and sisters. 

This doctrine is taught clearly by Joseph Smith as well as in LDS Temples.  LDS Temple clothing is recommended while attending events at LDS Temples.

At a time of great religious confusion, Joseph Smith is inspired to pray to ask for guidance regarding which church he should join.  As an answer to his prayer God the Father and Jesus Christ appeared to the boy Joseph.  One important doctrine that this event taught was that God and Jesus are separate persons and that God does talk to His children in their times of need.  This doctrine is also taught beautifully in LDS temples.