I know this is long, but please read it. I think it will explain a lot of what you are concerned about regarding the Christian belief of hell:
First of all, God would never punish someone for "not knowing how to believe". There is a verse in the Bible itself that says that God would not cast anyone out of His presence who never had a chance to learn of Him. So what you're saying there is incorrect. I can see how you might take this doctrine the way you do; I can understand the way you are perceiving this. But that is not how it is intended. You have to understand Christian doctrine in its entirety to understand the concept of hell/eternal separation from God. It's not a scare tactic or a way for God to force people to believe/worship Him out of fear. To Christians, God is holy, pure, light, and love. There is absolutely no darkness whatsoever within Him, nor can anything "dark" (i.e. sinful) be in His presence. Darkness and Light cannot coexist simultaneously. I am speaking metaphorically and I hope this is making sense. According to Christian belief, sin is darkness and separates us from God. We have to be completely pure to be able to be in His presence. But there is not a single person who ever lived or who ever will live (besides Christ, according to Christianity) who can live an entire life without sinning at least once. Sin being: lying to someone, being envious of others, coveting the possessions or success of others, stealing from others, etc. Everyone does these things. So what are we supposed to do if we are naturally sinful, but being sinless is the only way to be in the presence of our Creator after we die? In the Old Testament, God offered a way to atone for our sins: sacrifices. The Jews in the Old Testament would sacrifice the first born male calves (or sometimes there were other things you could sacrifice if you couldn't afford a calf) which had to be the absolute cream of the crop. They would kill the calf and offer it up as a sacrifice for their sins. This was symbolic because according to scripture, the wages of sin is death (meaning spiritual death or hell/eternal separation from God). Offering up the animal sacrifice was also symbolic of the Ultimate Sacrifice that was to later come, which was Jesus Christ. Christians believe that Christ is God in the flesh, who took on a human body and lived a completely sinless life. He was murdered in the form of crucifixion for claiming to be God. The scriptures which date back thousands of years before the birth of Christ prophesied of Christ's birth, life, atoning sacrifice, and resurrection. Christians believe that the death of Christ served as the ultimate sacrifice for sin. Jesus said that whoever believes in Him and accepts the sacrifice He made also accepts the forgiveness that is offered through His sacrifice, and so symbolically and spiritually, they are pure again and can be with God when they die. People who choose NOT to accept this don't have their sins forgiven, so when they die there is no way for them to be able to be in the presence of God again. I don't believe that Hell was created as a "punishment" for "bad people" or people who won't believe in God. I think what Hell is, is that people who die may realize that they are now eternally separated from their Creator, and it would cause a lot of mental anguish knowing that they don't have a chance to go back and make a difference choice and that that separation is forever.
I hope that that makes sense. I don't know if it makes it any less offensive to you, but hopefully it will at least give you a clearer understanding of these beliefs.