Thank you ... I just always hear that LDS believe that God used to be regular man on a planet and was exulted, an Jesus is the son of Lucifer. These definitions of "God" and "Jesus" would not be the same as the bible.. Are you saying that LDS don't believe that ?
One of the main tenants of the LDS Doctrine is a principle called "Eternal Progression." This tenant teaches us that the atonement of Christ made it possible for man to become perfect like He or our Father in Heaven is.
There are many passages in the Bible that will help us to understand this principle. I will quote a couple of them:
Matt 5:48
"Be ye therefore perfect, even as your Father which is in heaven is perfect."
Here we can see that Jesus is telling us to be perfect. Obviously, we are not at the moment, but if we follow in His footsteps we can become perfect.
Our Father in Heaven is God, therefore, becoming perfect like Him is to become a god. This is Eternal Progression.
Ephesians 4:10-13
"...Till we all come to the unity of the fatih, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ."
Here Paul teaches us that we should live the gospel in such a way that we become a "perfect man" like Christ.
Christ is God, therefore becoming a perfect man means to become a god.
The other important LDS tenant connected to this is that men and women were begotten by God the Father as spirits. Hebrews 12:9 tells us that: "...shall we not much rather be in subjection to the Father of spirits..."
As spirits we could look at God the Father and see his perfection and goodness etc. and we wanted to grow to be like He is. So He created a plan for us to obtain a body (coming to this earth) and prove our faith and progress to the point we could be perfect like He is. That plan included that Jesus would sacrifice for us to fulfill the law we could not fulfill ourselves. Jesus, thus provides a means to repent of our sins to gradually perfect ourselves in Chris and the means to obtain an immortal physical body (ressurection) and eventually become perfect like our Father which is in Heaven.
I hope you make the connection that: As man was made in the image and likeness of God, it means that we are in every aspect like God is, except we are not perfect like Him yet. Therefore if we are in His likeness it means that He was once like we are now and through eternal progression became who He is now.
This is the doctrine that explains what you heard. This is a nutshell, if you need I can elaborate on that.