This is a YES or NO question.
Are both of the following statements true?
For Christians the one God is the Triune God.
For Christians the one God is the Father.
1. If yes, please explain how the one God of Christians is both a three person being and the one God is one person.
2. If no, please identify which of the above two statements is correct.
I can tell you that first state IS and the second statement IS NOT what is articulated by the classical expressions regarding the Trinity that we see articulated by Athanasius and others.
But I also need to comment on your questions that follow. You see the first one simply does NOT make sense. The Trinity does NOT say that the one God who is triune is
both a three-person being
and one person. Rather it says that there are three persons
in one being. That is something very different than your first question.
Thus, I must disagree with Nathan's answer as well:
To us, there is but one God, the Father.
1 Corinthians 8:6
It is true there is but one God, but though he quotes scripture, he misapplies it. When one says that the Father is God, this is true. But when one says that God is the Father and stops there, it is true only as far as it goes, yet to fully describe God it needs to go farther. We cannot forget Thomas' statement in John 20:28 when he greets Jesus following the resurrection: "Thomas said to him, 'My Lord and my God!' " Thomas is not just giving praise to God the Father in greeting Jesus, the verse tells us that he is actually speaking TO Jesus and address him as "my God". And Jesus affirms Thomas in what he said, "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed."
Also, as Teral like to point out, the Word was God. What he fails to somehow understand is that Jesus is identified by scripture as this Word who is God (see John 1:1-5 & 14). So, again we have Jesus presented as God.
Even God himself refers to the Son as God. If one reads the opening chapter of Hebrews we see that God (the Father) is speaking of the Son in verse 5 and following. And in verse 8 we read:
But about the Son he [God] says, "Your throne, O God, will last for ever and ever..."
To me, it seems clear that God is calling the Son God.
So scripture itself is refering to the Father to whom Jesus prayed as God and Jesus who is the Son as God. Thus we have both the Father and the Son being referred to as God in the scriptures.
Add to that passages like Peter's conversation with Ananias in Acts 5 where he says,
Ananias, how is it that Satan has so filled your heart that you have lied to the Holy Spirit and have kept for yourself some of the money you received for the land? ...You have not lied to me but to God.
So, at least in Peter's mind, lying to the Holy Spirit is the same as lying to God.
Yet, scriptures also clearly proclaims that there is just one God: "Hear, O Israel, the Lord our God is one Lord" (Deuteronomy 6:4).
Faced with these different passages the early church tried to make sense of them and their experience. And they were left with just a few options, either:
1) The revelation that God gave to Moses was wrong, had been passed down wrong, or wasn't truly a revelation from God. This would mean that they could have more than one God and all would be well. But the church simply knew this wasn't true. They were too Jewish to even consider that concept for more than a moment.
2) Despite Jesus' own claims, the experience of people like Thomas with Jesus, and the continued affirmation of his divinity that people like Peter sees in the resurrection (read Peter's Pentecost sermon in Acts 2 carefully and you will see that this is actually affirmed in the response he makes to the crowd), it must be that all of these people are wrong. Well, how can you be a follower of one whom you say is wrong? So, they were left with a caundry. There answer was the unique formulation that we have since come to know as the Trinity.
3) There is just one God, but he exists as three persons in one being. This was not as far of a stretch for the Jewish mind as we today seem to think it was. The key was the affirmation of the unity of God. In making this statement the early Christians were NOT trying to actually expand the concept of God to multiple beings, quite the contrary. They were trying to make sure that pagans who did worship multiple gods understood that even with their references to the Father, the Son, and the Spirit as all divine that they still were worshipping just one being who is the one true God.
The formulation of the Trinity was NOT, as some like to incorrectly state, that 1+1+1=1. Rather, if we are trying to represent it through some sort of analogy to mathematics it would be more like 1x1x1=1.
And, again IMO, I believe this is what we see in scripture. Look at Paul's comparing of the glory of the two different covenants
2 Corinthians 3
12Therefore, since we have such a hope, we are very bold. 13We are not like Moses, who would put a veil over his face to keep the Israelites from gazing at it while the radiance was fading away. 14But their minds were made dull, for to this day the same veil remains when the old covenant is read. It has not been removed, because only in Christ is it taken away. 15Even to this day when Moses is read, a veil covers their hearts. 16But whenever anyone turns to the Lord, the veil is taken away. 17Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom. 18And we, who with unveiled faces all reflect the Lord's glory, are being transformed into his likeness with ever-increasing glory, which comes from the Lord, who is the Spirit.
Paul speaks of "the Lord", but sometimes it is obvious that he is speaking of the God of Moses, other times of Jesus, and at the end of the passage of the Spirit. So, all are the Lord, but there is never the implication that there is more than one Lord. Hence, though the term is not used in scripture, we see a presentation of God that is exactly what is expressed by the more formal doctrine of the Trinity as it becomes articulated in the 4th century.
But some things we must never do is to misunderstand the Trinity to say that there are 3 different beings who are God or that there are different degrees of greater and lesser gods or even that anyone person is inferior/superior to another within the godhead.