The lack of a satisfying answer to this question is perhaps the single most popular reason for people who choose to reject God. God’s justice, God’s love, who knows, we’ll find out one day. Answers like this provide no depth. While some of them are certainly relevant components of the equation, they are not entirely sufficient. The question that people should be asking is “why doesn’t a Holy God send everyone to hell?”
First of all you are not a good person. No matter what you have done or think you have done, you are nowhere near good enough for God. R.C. Sproul said, “Why do bad things happen to good people? That only happened once, and He volunteered.” The only unfair thing that has happened to an authentically good person was Jesus on the cross, and he volunteered. We are all sinners and we all deserve the worst. Anything other than the worst is God’s mercy revealed. This world is so broken and so filled with pain and so evil and so destructive. No man is good enough without the blood of Jesus washing him clean. We are sinful people and God cannot tolerate sin. God is separate from sin and he will not allow it into his Kingdom.
Second of all, God’s mercy has allowed humanity to choose for themselves their own path. What is unfair about letting someone choose which road they take? A person who rejects God chooses hell. No one is sent to hell without choosing it. Romans 1 tells us that creation itself is evidence enough in a Holy Creator that ought to be worshipped. Every human being makes the eternal choice. Luckily for us, God is merciful enough and loving enough to let us choose Him.
Third of all, just to emphasize the key issue, we all deserve hell and need a Savior. Faith and faith alone is the key to receiving salvation from the King of Kings. He died on the cross so that life would be unfair. If life were fair, every human being would end up in hell. Death died and Jesus saved us.