"What happens to me if I don't believe that Jesus is my Lord and Savior?"
The most important question that a person must face is how he will spend eternity. One question might be, what are we saved from? We are saved from the wrath of God, the dominion of sin, and the power of death (Romans 1:18, 3:9, 5:21, 1 Thessalonians 5:9). If somebody's answer is that they expect to go to heaven because they are basically a "good" person, that fails the test. Man is separated from God because of his sinfulness. Christianity is unique in teaching that man is sinful by nature, not good by nature. This certainly does not mean that man can do no good whatsoever, but that every aspect of our lives is touched by sin. We are guilty before God and deserve his wrath.
Some religions suggest that surely we must be able to do enough good for a loving God to let us in to heaven. Others suggest its living a decent life, loving your fellow man, born into a Christian family, attending church, performing religious rituals, etc. But the Bible makes it very clear that nobody is good enough. The Bible says that no one can even begin to stand before a holy God and proclaim self-sufficient adequacy.
If one truly believes in Jesus and receives him as Savior, he will also accept him as Lord - that is, Master - of his life. Belief will manifest itself. For example, true remorse for one's sinful condition will lead to repentance. The believer will acknowledge his sinful condition, will forsake his sins, and will put his trust in Christ for his whole life.
-Salvation is a free gift from God.
-When the Bible says we are not saved by "works" it is generally referring to works of the Mosaic Law (aka Old Testament). But this does not mean that obedience to God's moral commands is unimportant. Jesus, in fact, strengthened biblical commands for Christian living.
-When the Bible says that we are saved by believing in Jesus (John 3:16, etc), it is implied that to believe "in" Jesus means more than just intellectual assent. It means to believe "into" Jesus. In other words, it means to accept what Jesus says so fully and completely that you will obey his commands, however imperfectly we humans are able.
-An important passage is James 2: 14-26, which says we are not saved by faith alone. It suggests that there is a correct faith and an incorrect faith. "If someone says he has faith (but does not have works)" implies that just because someone says they have faith it does not mean that they have a sincere saving faith. James says that even the demons have what we might call head knowledge of God, but they do not have the type of faith that trust in God. James goes on to explain that faith without works is "dead." Thus, James is telling us that an empty faith does not save us, that we can tell is someone has a true faith by their good deeds which are evidence of a true saving faith.
The belief that saves us can be defined as "putting your trust in," which has a deeper meaning than merely believing a few facts about Jesus. Again, the demons also believe. In other words, they know that Jesus is God. However, they are not saved because they do not "put their trust" in Jesus.
A saving faith will produce good works. This is not to say that it is the works themselves that produce salvation. Nor is it to say that we can boast about our good works, which will always be inadequate.
Because of man's sinful nature, it's a wonder that God provided a way for anyone to be saved. There are no innocent people. But the Bible makes it quite clear that anyone who has heard of Jesus and then rejects him is doomed. That is tantamount to rejecting God and his offer of salvation.
We simply can never be good enough to be saved by our own efforts. Rather, in regards to justification, Ephesians 2: 8-9 is quite clear: "For by grace you have been saved through faith. And this is not of your own doing; it is the gift of God, not as a result of works, so that no one may boast." We are saved by grace through a living faith in Jesus Christ alone, while warning that anyone who thinks that they are saved by a mere profession of faith without seeking to be obedient to Christ and his church has a false sense of security.
We could say salvation has 3 components:
1) Believe: "Truly I say to you, whoever believes has eternal life." - John 6:47
2) Repent: "...repentance for forgiveness of sins." - Mark 1:4
3) Follow: "Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God abides on him." - John 3:36
Again, it is faith that is the tool that links us to God. But it is not the amount of faith, but the object of your faith - Jesus Christ - that is important.