I have included the text below which came from a talk given by Pres. Gordon B. Hinckley (1910-2008), given in October 1998. I hope it helps.
So, we believe in 3 separate beings but one Godhead with the same purpose which is "to bring to pass the
They each have a part in that purpose. It was Heavenly Fathers plan to let us come here to experience earth life and prove ourselves worthy to return home to Him being successful in that plan. He wants us to come home successfully so in order for that to happen we needed a Savior, which is His son ,Jesus Christ. Jesus paid the ultimate sacrifice for us to return home through the Atonement. And then, last but not least, is the Holy Ghost which is a comforter and helper for us while we are here on the earth so we can live our lives successfully and gain the knowledge we need to be able to return home to Heaven. That is the purpose of God for us here at this time.
There are three different beings and three different roles with one purpose, us!!!
Arguing with others over this point is of no use because its something that we can't scientifically prove. It is what we believe through our studies of scripture and experiences (testimonies) that we have gained while living life here. No one can change what you know. And I personally think as long as we believe and acknowledge that God exists then we are on the right path. The rest depends on what we learn and act upon as we move ahead in life. These are my thoughts,
In the name of Jesus Christ, Amen.