How do you know that there is a heaven and a hell? How do you know that Jesus is the Son of God? How do you know how to be pleasing to God? How do you know where you came from and where you are going, plus why you are here? How do you know that Peter and Paul were both apostles? You know all the answers to these questions because the Bible gives you the answers. Don't you need some other proof?. No, not if you believe that the Bible is God's special revelation to man! Do you need another testimony? No, the Bible is enough!
If you were to hear Jesus Christ say, "Thy sins are forgiven thee," how would you know that you were pardoned? Because Jesus Christ said so. Would you need other proof? No, because Jesus Christ said so! That is what is happening in Matthew 9:2, "And, behold; they brought to him a man sick of the palsy, lying on a bed: and Jesus seeing their faith said unto the sick of the palsy; Son, be of good cheer; thy sins be forgiven thee." The scribes that were listening to Jesus at that time were offended by what Jesus said, because they believed only God could forgive sins, and they were right. Only God can forgive sins, but they did not understand what they had seen and heard about Jesus Christ. Why did the friends of this sick man bring him to Jesus Christ? Because they had heard that He could heal people no matter what kind of illness they had and they believed that word they had heard.
Jesus confronted the scribes for the very thought in their heart. "And Jesus knowing their thoughts said, Wherefore think ye evil in your hearts?" Still yet, the scribes did not understand who they were dealing with, so Jesus Christ said to them, "For whether is easier, to say, Thy sins be forgiven thee; or to say, Arise, and walk? But that ye may know that the Son of man hath power on earth to forgive sins," How did Jesus Christ prove that He Was God? "(then saith he to the sick of the palsy,) Arise, take up thy bed, and go unto thine house." Notice the belief of the man who was sick, "And he arose, and departed to his house." How did this man know that he could get up and walk home? Because Jesus Christ said so!
This same Jesus Christ says that in order to be saved one must:
1) Believe in Him as God's Son (John 8:24).
2)Repent of sins (Luke 13:3,5).
3)Confess Him before men (Matthew 10:32).
4) Be baptized to be saved (Mark 16:16).
Jesus Christ promised to save one who obeys His Words. Nothing else is needed!