There is only one Being of God.
This one Being of God is complex, not simple, so that God subsists in the three uncreated, co-equal 'persons' of the Father, the Son, and the Holy Spirit. But one Being. This is the God that Christians adore. This is the God Jesus came to Earth as a human for - to show us the way back to God. This Jesus is the exact representation of God, in the flesh. We learn about God through putting all our faith in Him, the uncreated Son. The uncreated Holy Spirit enables us to understand such things, as Jesus promised He would (after Jesus returned to the Godhead in Heaven).
If the Son was a different Being to the Father and the Holy Spirit, then you would have polytheism. Three gods. The Bible utterly condemns polytheism, stating clearly that we worship the one Being of God alone. This is the most complex theological matter we can think about because the Almighty is complex, not simple. If we could describe the Almighty and completely understand who He is, then He would no longer be the true God - he would be a figment of our own thinking.
As there is only one Almighty God, the easiest way to break down the idea is to go to the scriptures where it states that the Father is a Mighty One (Isa. 10:21), the Son is a Mighty One (Isa 9:6) and the Holy Spirit Paraclete is a Mighty One (Jn 3:5-11 with Acts 5:4). Three 'Mightys' make one ALmighty!