The best place for anyone to start is by reading Genesis chapters 1-3, and then to read John's gospel, asking (1) if the accounts ring true or sound cooked up, and (2) if Jesus is genuine even though he sees himself as one with God. If anyone knows what's true about God, God must know. If Jesus is God, then what Jesus says, God says. If Jesus sees the writings of the Old Testament as God's words, and if he commissioned His special missionaries (or "apostles") to pass on His teachings (ie the New Testament), then what the Bible says (Old and New Testaments) is what God says. In a nutshell this is what it says.
God, who is pure goodness and love, made us for a loving purpose. It's not all just an accident. The Bible is clear, though, that we have all been born with our backs turned to God - to God, Himself, who loved us and made us and all the world! We inherited our father, Adam's, defiance, and our defiance has blossomed as we've grown up, and we all deserve to pay for that. But although many will rightly pay for it in Hell - what's amazing is that some won't. We all certainly deserve no end of punishment, but believers are mercifully spared.
However, believers are saved from Hell by grace only - ie it's free: it's the complete opposite of what they deserve. They don't pay a cent for it, even if they could. Our arrogance in turning our backs on God is so serious that nothing we do could make up for it. In fact, people's pathetic little attempts at making amends and buying God's favour are offensive to Him. But God Himself sees to the price: He gives believers salvation for free, and "foots the bill" himself. God the Son, Jesus Christ, in his death by crucifixion, paid the full price and actually bought the free salvation of anyone who truly believes in Him. He took their punishment so that they would be spared from Hell.
What incredible love. "God showed His love for us in that while we were still enemies, Christ died for us." (Romans 5:8) What is amazing, too, about God's love, is that we were such prisoners of our defiance, that, left to our own devices, we would have refused to turn to Him and be saved. He had to "draw" us even to believe in Him (John 6:44,65)!
To believe in Christ means to come to God (1) bowing down to His absolute authority and begging to be spared, and (2) trusting Christ to have paid the price for you to be spared - ie (1) you're not rescued if you're not serious about turning your back on sin, and (2) you're not rescued if you try to do things to help earn it.
One day every single person will stand before God the Judge. But the believer has a clean record. Jesus took his punishment for him, and thereby bought him a clean record in God's court. Even tomorrow's sin is already punished. He's clean in court forever. Jesus said, "I'm telling you the truth, he who believes has eternal life." (John 6:47)
In the meantime, when He gives someone eternal life, he gives him His Spirit to lead him. God, the Holy Spirit, takes up residence right at the heart of him, and changes him, reshaping the very way he thinks. He gives him a passion for God and His law. He works to make the believer more and more like Jesus - but it doesn't happen overnight. It's a long tough road, BUT, while you are still being cleaned inside you are always clean in God's court.* And so you are always His dear child and He's glad to have you talk with Him anytime at all. [* Press here for more help to understand these two cleanings.]
