I grew up under Baptist Christianity, and my dad (an INTJ) has been exploring ministry work for some time. However, neither of us subscribe to the "fundie" Christianity; he was more interested in actually studying the Bible, not taking what the preacher said at face value.
Through numerous Bible studies at home, I've come to understand a key secret about the Bible: to fully understand the Bible in context, you have to understand the background of the writer or the passage. Each writer lived in a different culture, and each passage ties to that culture or something written elsewhere in the Bible.
So on that note, I thought I'd contribute to the discussion by sharing the rational Christian's answer to how God's existence relates to our universe. It is a bit long, though. This was as short as I could edit it.
(Before anyone argues, I'd like to point out that the term "fundie" is often applied to irrational Christians, and I try to avoid them as much as I can.)
It says in the Book of Isaiah that prior to creating the universe, God had his own eternal realm, Heaven, populated by what we call angels. He created the angels to be a creature that would love him unconditionally and of his own will.
His Number One angel was Lucifer, regarded as the most beautiful of the angels. Lucifer tried to overthrow God out of jealousy, forcing God to banish him and the third of the angels that rebelled with him. Lucifer became known as Satan, and his angels became twisted into demons. God creates a new realm referred to in the Bible as a "lake of fire" as punishment for their crimes. However, they will not be sent to it until the end of our universe.
Instead of creating a new Heavenly creature, God created a whole new universe centered around a single planet, Earth. God went to all that trouble because he wanted to create his new creature, man, in an environment all his own. However, man still retained the same purpose as the angels, so he still had the unconditional-love capabilities and freedom of will as the angels.
When man disobeyed God, God condemned man to the lake of fire with Satan and his demons. However, Adam's sin was not out of direct hatred of God like Satan's was. His motive is never stated in the Bible, but I'm thinking it may have been so Eve wouldn't be punished alone.
Because of this, God creates two new realms: Paradise and Hell. God condemns man to share Satan's punishment, but offers man a respite.
If man continued to love him, he would placed in Paradise at the end of his life. After Christ's crucifixion, Paradise is eliminated, and this group (officially termed "believers") is relocated to Heaven. Now when a believer dies, he spends eternity with God himself.
Christ's death was meant to be God's love sacrifice to man, in essence meeting man halfway. Now, instead of having to kill lambs to prove his love, man needed only do for God what God had done for man; acknowledge Christ's sacrifice as God's display of love to man.
When a person does this, God implants a version of himself (the Holy Ghost) into the new believer, giving the believer a way of having a relationship with God before dying and joining him in Heaven.
If he rejected God, God would have no dealings with him. Upon death, these people would be placed in Hell, which will later be rolled into the lake of fire with Satan and his demons. This will happen after the universe reaches its end as described in Revelation.
Satan hates God and everything God loves, including man. Satan also knows that he is doomed to be punished. He also knows that God still has love left for unbelievers. If he's going down, he might as well give himself as much company and God as much heartache as possible in the meantime. When they die, God's not gonna do anything with 'em, so...
The result in the end will be God merging his Heaven with a newly-purified Earth, turning everything into Genesis 2.0.