You cliam that all Christians believe Jesus is God? Think you'll find most say he's the Son of God, and not God incarnate!
First, I should be careful not to use terms like "all", "always", "none", and "never" as there always seem to be one or two exceptions to all of these terms so that none of the are a good choice, never.
Second, I don't believe the terms "God" and "Son of God" are mutually exclusive.
Third, yes I am of the opinion that Christians believe Jesus is God incarnate, that is exactly what Christmas is all about -- he shall be called Emmanuel, God with us. I also believe that believers will call Jesus the Son of God. I believe that we see Jesus called both in scripture:
Thomas said to him [Jesus], "My Lord and my God!" (John 20:28)
Not only did Thomas address Jesus as God, but Jesus accepted it and told Thomas that other who would believe as he did blessed for doing so.
Then Jesus told him, "Because you have seen me, you have believed; blessed are those who have not seen and yet have believed." (John 20:29)
Then, John, the author of this Gospel, goes on to say that all that we have read in his Gospel is written so that we may believe that Jesus is the Son of God:
Jesus did many other miraculous signs in the presence of his disciples, which are not recorded in this book. But these are written that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name. (John 28:30-31)
So, you see that BOTH are part of our Christian belief system. They are not mutually exclusive thoughts -- at least not for those of us who would be called people of the Book.
Avar, I am not here trying to convince you that the statement that "Jesus is God" or that "Jesus is the Son of God" is a true statement, or a "fact" as is presented here. But it is a fact that Christians believe they are true. If you believe otherwise, then you are not as familiar with Christian beliefs as you might think you are.
Has this ever been discussed and debated among Christians? Yes. And at the time they were debated, those who thought otherwise found themselves in the minority and were labelled as heretics. You are entitled to think that the minority was right and the majority wrong. But you are being dishonest with yourself and with Christian history if you think that Christians think other than what I have hear restated: Jesus is God incarnate among us. Jesus is the Son of God. jesus is "True God from true God", "Of one being with the Father". As to his nature, both divine and human.