In the beginning, God created the Heavens, in other words the purely spiritual planes of existance known as Heaven and Hell (as well as possibly others) and the entire physical plane of existance includings stars, planets, and the laws that govern them. This is the totality of the Universe. Within this physical plane, exists the planet Earth in which we humans reside. Since the beginning of life on this planet, all life has been given souls. However it wasn't until mankind came into being that a living being's souls had the possibility of extending past our physical bodies and therefore became capable of transcending itself into the spiritual plane. God has given us souls that were designed to exist through out eternity. We were designed to be born in the physical plane, and then therefore through time would later transcend this plane into the spiritual plane known as Heaven, much like how a fetus is formed into a human within a mother's womb, and then finally given birth to.
Some time before mankind's existance, there existed a great Angel, a member of a race of spiritual beings who are to our knowledge, born in Heaven. He was once known as the greatest and most powerful of all Angels, and his name was Lucifer. Lucifer's greatness got the better of him, and he one day believed he was greater than God. He gathered a mass of Angelic followers, and attempted to overthrow the mighty God. There was a great battle that raged in Heaven between the Angelic followers of God, and the Angelic followers of Lucifer. Needless to say, God won, and therefore he ran Lucifer and his forces out of the Kingdom of Heaven, preventing Lucifer and his followers from ever entering the Kingdom of Heaven again. To our knowledge, there were only two possible domains left for him: Earth and Hell.
Lucifer was from that point on refered to as Satan, and his Angelic followers were now called Demons. Considering the book of Revelation and it's passages concerning Armageddon, the spiritual battle between God and his Angels, and Satan and his Demons, will result in the end of the Earth. It will be the ulimate end of the physical world, and therefore the end of time. Also keep in mind that although God is much greater than Satan, Satan is considerably powerful, and is considered to be the second most powerful being in existance. For them to fight it out in the beginning would mean for them to demolish most if not all of the physical plane, and therefore God and Satan's final battle is scheduled for a later time. Keep in mind, we do not know whether Satan's dominion is simply on Earth alone, or whether his domain stretches beyond Earth to other planets with life as well. If the second scenario were to be the case, which is the most likely scenario in my opinion, then the final battle could be set for far longer than we thought, and could be a universal event as opposed to a planetary one. Now, due to Satan's hatred for God, and their inability to combat him from where they are, their only course for retaliation was through killing his beloved children existed on the physical plane.
The most effieciant way of doing so is through deciet and temptation, (since no spiritual being can intercede with another's free will, and we ourselves are in fact spiritual beings contained in a spiritual form) so that mankind would multiply and therefore supply more lambs for the slaughter. Humans were originally put here in imperfect bodies yet we were still innocent and pure due to our lack of knowing the difference of good and evil. We were literally God's innocent little children. However, Satan tempted and decieved mankind into learning the difference of good and evil, and then proceeded to tempt and decieve mankind repeatedly since the dawn of our existance on up to modern day. Due to his constant temptation in his efforts to kill all of mankind, we have all become incredibly imperfect all while having the full capability of discerning Good from Evil. We have become the centrality between a spiritual stuggle of Rightiousness and Evil.
Since we are all imperfect and full of sin, we cannot naturally enter the Kingdom of Heaven. Perfection is good and equals life, imperfection is evil and equals death. Death does not mean the the ceasing of existance, it means pain and agony. In other words, we all suffer pain and troubles in life because we are all spiritually dead. Therefore the pain of Hell is not meant as punishment, Hell is simply the "spiritual graveyard" for those who chose death as opposed to life. Hell was originally designed for Satan and his demons, not for mankind. God's ultimate goal is peace, harmony, beauty, love, fellowship, happiness, and therefore life; which to those who can comprehend the difference in good and evil can only be found in perfection. God made Hell as the domain for those who chose death, and he made Heaven as the domain for those who chose life. Now, we are all imperfect, and therefore we are all already spiritually dead. We are all capable of perfection, which has been proven by God himself appearing in the human flesh (a.k.a. Jesus), however none of us are perfect, and none of us will be perfect as long as we remain on this Earth.
Our only hope is found in the love of Jesus Christ, the only "human" who ever was perfect and good, and therefore is the only human who deserves life. Yet he suffered all the pain of all of our deaths, for the sole purpose of giving us a chance at life. He did this because God loves us despite our incredible imperfections, and is willing to accept the dead into his Kingdom, on the premise that we accept Jesus Christ as our lord and savior. All we need to do, is promise to love, honor, and follow him for all eternity so that one day we will reach perfection, and so that we can live forever in peace, harmony, beauty, love, fellowship, happiness, and therefore eternal life.
In the end, all life on the physical plane of reality will cease to exist, and so will most likely the entire physical plane itself as well. Before the precise end of it all, God and Satan, as well as both of their armies, will battle it out for supremesy in which God will ultimately be the victor. Satan and his demons will be confined to Hell for all eternity, where as God and his followers will live in eternal peace and tranquility.
This is God's ultimate goal. The past, present, and future; and therefore the meaning of life itself.