Dear ahmadhassan,
I think your question is quite sincere, and I shall try to answer it the best that I can. Now, I will start with the very basics, so please bear with me, if you already know this.
**1) Is there
one God or three Gods?
The Christian answer is, that there is one God, and there is not three Gods. This might seem trivial, but it’s important, because God must not contradict logic! God can be one God and three persons, but he can never be one God and three Gods.
2) Does God have a son?
To answer this, we must first decide: What do we mean by a son? Muhammed quite rightly refused to believe that God had a son in the same way that Zeus had sons and daughters. He was correct in not believing, that Jesus was the result of God having a sexual relationship with Mary. To propose such a thing is blasphemy! God is not flesh and blood! God is spirit.
But Christianity believes that Christ existed
before entering Mary’s womb. Jesus has always been. He was present at creation, he was before Abraham.
What then do we mean by son? Let me use another image, that is also used for describing, whom Christ is:
-God exist.
-God is rational, that is he can think he can understand, he can percieve things and he can percieve himself.
-God is perfect, therefore also God’s thoughts, God’s perception is perfect.
-Man is imperfect, and thus, man’s thoughts are imperfect. So when man percieves something, his perception is never quite right. There is something missing.
-Now, imagine a man who comes to the full realization of himself. He has now a perfect perception of himself. Yet, man’s image of himself is still not completely like the man, because his perception is
lacking existance.
-God’s perception of himself on the other hand, is complete in all aspects, and therefore it also exists.
-Thus there exists: God
and the image of God, God’s self-perception. We call this self-perception God’s “Logos” which is Greek for “Thought, principle or (literally) word”
Must not this Logos be said to be God? And must it not also be said that it is the same God as the “original” God? Must not also this thought (Son) be said to be a different person than the thinker (Father)?
So in this sense, God does have a Son. We use Son rather than Logos, because we not just want to communicate the rationality of the Trinity, but we want to communicate, the love between them. Also, Son in Israel meant to be of the same essence. Therefore the Pharisees where quite right, when they concluded, that Jesus made himself equal to God.
3) Is there a Holy Spirit?
If we mean by Holy Spirit, that God is a “dualist” essence, which can be parted in a “body” and a “spirit”, we are quite wrong. Rather, the Holy Spirit is the name given to the third person of the Trinity, who springs from the relationship of the Father and Son.
God is love, we say and that is according to Scripture, but for God to be love, there must be a lover and a beloved. Now (what a coincidence

) we just discovered that God is both Father and Son, and it
is between these two, that the love which is God exists.
Sometimes among humans, we might notice that there is a special bond. Something that unites and “animates” in a certain sense. For good or evil. Take for instance a football team. There is something “in the air” when the team is together, which is not there when they are apart. A certain way of behaving… a certain understanding, intimacy. And it resembles an actual person quite a lot (though in human relationships, it isn’t.)
In God, however, the love between Father and Son is an actual person. Therefore, God is the lover, God is the beloved, and God is love. But there are not three Gods, only one God within whom there are three persons.
We say, that God the Son is born of God the Father, and that the Holy Spirit flows from the Father and the Son.
4. Whether the Father was before the Son and the Holy Spirit
God is perfect.
God therefore can never and has never changed.
Thus God’s perception of himself has always been the same.
Thus the Logos has always been.
The relationship between the Father and Son has always been the same.
Thus the Holy Spirit has always been.
(On a side-note, it is not right to think of God as being in time. There is no before and after for God, because for time to exist, change is required, and there is no change in God. Rather, time exists in God. The argument is still valid, however, and a little easier to understand

)