If Heaven really does exist, do you think you're good enough to go there? Well, let's find out.
If you've lied, stolen anything, taken God's name in vain, or looked with lust (which God considers adultery), God sees you as a lying, thieving, blasphemous adulterer at heart. You see, God's standards are so high that no one could ever be good enough to get into Heaven on their own.
God doesn't care if you change your lifestyle. He demands repentance and righteous living anyway. So, you should change your lifestyle to fit the Word of God. We were created for His glory and His honor. However, we have all sinned against Him; therefore none are good, and all are worthy of Hell.
Put yourself in a court of law. You have committed murder and have been proven guilty. You plead with the judge to set you free by saying, "I know I've done wrong, but I won't murder anyone ever again. Please let me go!" The judge is going to respond to you by saying, "That's good that you've decided not to murder anymore, but you still killed that one person. I must see that justice is served. You're going to have to go to prison."
If God were to let you into Heaven just because you changed your lifestyle, He would be a corrupt judge. However, God is perfect and just; therefore He must see that justice is served.
Go back to the court scene and imagine that you are now being led out of the court and off to life in prison. Suddenly, someone you don't even know runs in and pays your fine. The judge can now turn to you and say, "You're free to go!"
In order to be set free, you first had to realize that there was nothing you could do to save yourself. Secondly, you had to transfer your trust from your goodness to the other person's money.
That's exactly what Jesus did for you. You sinned against God. As of now you are guilty, and there is noting you can do to save yourself. Two thousand years ago, Jesus realized that. You see, God sent His only Son, Jesus, to suffer and die for your sins--that you might be forgive and set free. All the weight of your sins was placed on His shoulders. He took the punishment for your sins, and paid your fine with His life's blood.
There's only three things you have to do to be saved:
1) Realize that you cannot save yourself.
2) Transfer your trust from your goodness to the blood of Jesus.
3) Repent (turn completely from your sin).
The very second you do those three things God will forgive your sins and grant you everlasting life.