Trinity Vs. Supposed Sin of Shirk?

Continuing on with this month's topic, I need to show that God is triune and not a single deity. The best place to start is at Christ's baptism.

Matthew 3:13-17 (KJV) describes the scene this way. "Then cometh Jesus from Galilee to Jordan unto John, to be baptized of him. But John forbad him, saying, 'I have need to be baptized of thee, and comest thou to me?' And Jesus answering said unto him, 'Suffer it to be so now: for thus it becometh us to fulfil all righteousness.' Then he suffered him. And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him: And lo a voice from heaven, saying, 'This is my beloved Son, in whom I am well pleased.'"

Now how could God be a singular entity when the Spirit of God and Jesus were in the same place when God spoke from heaven?

Likewise, God spoke from heaven in John 12:28 (KJV). "'Father, glorify thy name.' Then came there a voice from heaven, saying, 'I have both glorified it, and will glorify it again.'"

But Qu'ran 4:116 says, "Allah will not forgive that partners be associated with Him; but will forgive anything less than that, to whomever He wills. Anyone who ascribes partners to Allah has strayed into far error."

Also, how could the Old Testament address God in the plural form (read Genesis chapter one) and show himself to be a triune being in the New Testament, yet the Qu'ran claims he has no partners? If God and Allah were the same being, he himself would be guilty of the sin of shirk, ascribing partners to himself.

I'll be writing more about this in my next book called You Think You're Going to Heaven? Foolish Christians believe that God and Allah are the same but I've shown here without equivocation that they aren't.