How can three different people be the same?

Well, the Holy Spirit isn't really a person, per-se, but a figure, a spirit. To me, I picture that spirit being God's. Jesus was God's son, but he was a part of him as well. This is mainly a faith thing.

What does the Bible say about God's reason for having a son?

Jesus wasn't God's physical son. He was given to Mary and Joseph by means of her giving birth to him. You can't think of this as his being a fetus when given to Mary. He grew inside of her like any other baby. It isn't really physical. Jesus was all human, but he had a piece of God inside of him, hence him being the son of God. He had a connection and was placed on Earth for one purpose. To die for everyone's sins. His body or human part, was ascended into Heaven, and what happened after is uncertain. His body isn't on Earth though. It has been proven that he existed, and that he taught and preached.

What is the significance of the Holy Spirit in the Trinity?

Like I said, to me the Holy Spirit is the spirit of God. So technically, it is him. It's mentioned in the Bible that the spirit entered a disciple as a blue flame. So, it's more of a how you see it thing. I see it as, well, nothingness inside God, that when entering others, appears as a blue flame, or atleast when Jesus was alive. Now,when you accept Jesus into your heart, he just is there. The Holy Spirit becomes a part of you. It's not a physical thing, but you just feel better and more pure, even though nothing physical happened.

Sorry if I'm wrong on anything. I just tried to help and explain what I believe. A lot of things in Christianity are based on faith and just the way you picture things. I say again, not everything is physical. :)

Hope I helped!

For what sins did Jesus die for? Did Jesus die for the sins made before his death and resurrection? Do Christian sects view Jesus differently, or is it all the same view?

I'll try answer to my understanding. (1)He did die for original sin, but also all the sins of mankind/humanity in the future. So, as long as you truly repent or have done no wrong you will be accepted by God. (2) Yes, different dominations view Jesus differently, although I'm unsure how.

(Hope I helped)

Also, the film doesn't represent any facet of decent peoples or religion. I wish that bigoted people would just shut up and let religion be for peace, not their propaganda tool. D:

I'm a Christian, but whenever I hear about the Holy Spirit, it's described as a bright light. Hmmm... I need to look into that. But, if you can find a Bible anywhere then read Revelations, it has wonderful descriptions of Heaven. Jesus will save you, PM me to find out how. ( This not meant to be offensive in any way.)

Well most people(especially Atheists)has been asking that question, but as once a Christian I tell you this,
The holy trinity isn't telling that there are three Gods in Christianity but rather they Homogenous they are one, so that's Catholics have been calling it 'Holy Trinity one God'
I'm a Deist but I'm once a Christian

I don't think any human could rightly answer the first question, the best explanation I heard compared the Trinity to a clover; three leaves, one plant. It's one of the great mysteries. Speaking of which, you also touched upon another mystery of faith in the second question, too. Jesus isn't "part human-part God," He is FULLY human and FULLY God. Yes, Mary is regarded as the Mother of God, and that's because she willingly carried and raised Jesus so He could fulfill His mission on earth. He has also existed as long as the other parts of the trinity, which means that he has always existed and always will exist (and, what do you know, another mystery!).

Now for the third question. The Holy Spirit is believed to be of the same nature as God the Father, but He has several symbols that are typically used to represent Him. The most commonly used ones are fire and a dove. The Bible mentions the Holy Spirit coming down upon people several times in the New Testament, like on Pentecost or Jesus' baptism. I'd research it, though, I'm sure there are things that I'm missing.

Mem

regarding your questions about the holy trinity, I think I can answer a few.
As a member of the church of Saint Francis of assisi I was tought that the holy spirit is in all of us, the piece of god in us, and i think it was first mentioned in the bible when the diciples were sent out across the world, it was the holy spirit that gave them the ability to speak every language.

Actually, in Christianity God isn't really thought to be "a bearded man," that's just how He is portrayed in most pictures. Also, we were made in His Image in the fact that we are able to think and reason, after all, it's what's inside that really counts.

-Mem

Well in Judaism (since I'm a deist and had some friends who are of different religions and this religion included) they portrayed God as somewhat a powerful deity either peaceful or warlike deity for sometimes God is called the Avenger and the protector of Israel sometimes he is the compassionate one, well to me religions around the world either Monotheists or Polytheists worship the same God as I quote this words I took from a book
"we are brothers all of us born from the same cradle yet here we are squabbling for our father's affection"