"It seems the only reason [God] created people was to have somebody to worship him. Christianity believes that we live to worship God and then we die and we also worship and work for God. That doesn't seem like much of a point to existence. I personally don't really want to spend eternity praising and working for a deity."
You are wise to raise this dilemma that plagues the minds of many Christians as well as non-Christians. I also appreciate that you are open and honest about how it makes you feel. I wish more people would come to these issues in that way. However, you have loaded your comments with several assumptions that need further examination.
Your concern really boils down to two interrelated questions. The first question is, “Why did God create human beings?” The second is, “What will we spend eternity doing?”
1. Why did God create human beings?
Was He lonely? Did He need human beings in order to fill some need in Himself? Or is He just so self-absorbed that came up with the idea of creating humans to sing His praises and do His bidding for all eternity--and if they would refuse to do that, He would at least get pleasure out of torturing them forever? Based on your original comment, I imagine that such descriptions of God are repugnant to you. Who could believe in such a terrible being? Well, it may surprise you to know that I also find these descriptions abhorrent, and even if I could believe in such a god, I would have no desire to worship such a being. We both reject that picture of God. Fortunately, it is not the historic Christian understanding of God.
A. Was God lonely?
God was neither lonely nor did He need human beings in order to fill some need in Himself. These questions may remain problematic for unitarian monotheists, but not for Christians, who are trinitarian monotheist (sorry for the $10 theology vocab words). The historic Christian understanding of God is that there is one God who exists in three eternally distinct persons; Father, Son, Holy Spirit. This is traditionally called the Trinity. Now, I want to preempt a possible knee jerk reaction which might go something like, “the Trinity is a logical contradiction.” No, it is not. Say what you want about it, but it is not a contradiction. I admit that it would be a contradiction to say “there is one God and there are three Gods.” The law of identity precludes the possibility that God could be one and three in the same way. However, the Christian teaching is that God is one in essence and three in person. That may be difficult to grasp, but it is not logically problematic. And really, I am just throwing this in to be thorough. It would suffice to say, for your concern, that the Christian view of God is that He is a Trinity. Therefore, God has always enjoyed community and experienced the giving and receiving of love. That means that, on the Christian view, that God created human beings not out of need, but as an overflow of what He already had--to invite them into that perfect love relationship--what C. S. Lewis beautifully called “the Great Dance.” And I do not think it is a coincidence that all human beings naturally long for that sort of relationship; where love is given and received unselfishly; where we can be known and know another without inhibition; forever. If hammers had consciousness, we can imagine that they would long to hit nails into planks of wood. Why? Because that is what they were designed to do. In the same way, human beings were created to be in a love relationship to God.
Now, to save space, I will assume that you know the Christian teaching concerning the fall of humankind into sin and the severance of that relationship with God. Furthermore, I imagine that you also already know that Christians believe that God the Son took on flesh, lived a perfect life, gave His life, took upon Himself the just punishment for the sin of all who would trust in Him for salvation, and resurrected from the dead 3 days later. In short, He said, “You broke the relationship by doing evil. Evil demands to be punished. But I will take the punishment in your place in order to restore the relationship.” With all of that in mind, I don’t think the Christian teaching about why God created human beings could be any clearer. God the Son took on flesh, become a servant, died a criminal's death, and bore the wrath for our sins, in order to bring us back into that relationship. We were made for a love relationship with Him.
B. Is God just self-absorbed?
Given that God created us for a love relationship with Him, where does the feeling that God is a celestial dictator, demanding allegiance or else, come from? The obvious biblical answer is that it is the very lie which with the devil tempted Adam and Eve (Genesis 3). That is, the idea that God just wants to keep us under his thumb. We cannot seem to shake that idea, even today. God wants us to worship and serve Him? How dare He? He must be a self-absorbed celestial dictator! You said as much yourself, “I personally don't really want to spend eternity praising and working for a deity.” That is just the way it naturally feels for us.
But is that the historic Christian understanding of what it means to be in a relationship with God--forced allegiance and labor? No. That is like saying (as some people do), “I really don’t want to get married and spend my whole life catering to the whims of some other person.” Is that what marriage is? Unfortunately, it often is the case in a broken and fallen world. But we all know that in a perfect world, marriage would be a relationship where we serve and love one another because we want to, and it would bring us great joy to do so. Again, I don’t think it is coincidencidental that we all long for that sort of relationship. We were created for that. Thus, from cover to cover, the Bible compares the relationship between God and His people to the covenant of marriage. Is a husband self-absorbed for not wanting his wife to sleep around with other men? Of course not. Why then should we think of God as oppressive and controlling for wanting his bride to give herself only to Him and not to false idols? To “serve”, “worship,” and “work for” God doesn’t mean joining a slave camp so you can bust up rocks all day while the rest of the world is free and having fun. It means entering in a relationship where everything we do demonstrates our love for Him.
You see, the real problem is that we have a warped perception of freedom and what it means to be human. It goes all the way back to the fall of mankind. We think that real freedom means doing whatever we want. We think that worshiping ourselves gives us the greatest power and makes us truly human. But these could not be farther from the truth. Let’s imagine that there was a fish who felt trapped having to always be in the water. Maybe she is a girl fish. Maybe her name is Ariel. I don’t know. Sounds like a good movie idea. Anyway, she swims up and jumps out onto the nearest beach. At last, she is truly free! Wrong. She will suffocate and die there. She would need to be transformed in order to free in that environment. As is, she is more trapped than ever. Why? Because she is only truly free and only truly able to be herself when she is in the environment for which she was created. We are just like that. We think that by doing away with God, we are truly free, truly human. But we are more trapped than ever, and slowly suffocating. Think about it practically. What happens to someone who literally always does whatever they want, whenever they want, with no inhibitions? The answer is not “they are totally free!” No. They become a slave to their own lusts--not to mention addicted to whatever substances, or lifestyle choices they choose to indulge--that is, if they survive for very long at all.
Anyway... what does this have to do with your question? Everything. True freedom and to be truly human means to do what we were created to do--to join the Great Dance--to forever love and be loved by God. Only in that state, every human being will realize his or her fullest potential. To be in relationship with God is not about suppression or oppression, but succession. The Bible teaches that we will receive new bodies and inhabit a new universe. So, that brings me very quickly to the second question, for which I will give only a very brief answer.
2. What will we do for all eternity?
We will do what we were created to do. We will reach our fullest potential. Contrary to some popular ideas, the biblical picture of eternity is not that we are going to be floating around in an ethereal white-space, bored out of our minds, laying on our faces, and singing from the Baptist Hymnal 24/7 for all eternity. The ultimate state of all who are with God is to inhabit new, glorified bodies, in a new, glorified universe. It is just wrongheaded to assume that serving God will be like serving a North Korean dictator. Quite the contrary. We will spend eternity doing amazing things that bring joy to our hearts and glory to God for all eternity--enjoying Him as He enjoys us. I could be totally wrong about the last thing I am going to say, but I like imagine that part of the reason the universe is so absolutely enormous is that God intended for his creatures to explore and enjoy (maybe even inhabit) every square inch of it. However, sin has limited our ability to do so in this time-space continuum, but I look forward to that possibility in the new universe. I just wanted to throw that in for fun.
And what about everyone who is not with God for all eternity? Precisely the opposite. They will be eternally haunted by the realization that they are not with God--not able to be who they were created to be and realize their fullest potential. Someone might say, “Oh, that sounds a lot nicer than literally being burned to a crisp or tortured in a medieval dungeon forever.” I’m not so sure about that. They will spend eternity away from God--out of the dance for which they were created--because they did/do not want Him. That should not sound like a nice option.