A person who becomes religious may do many thing that resemble repentance of sins. However, such a person is not turning from evil. He is simply turning from one form of evil to another more covert form of evil that manifests in hypocrisy and self righteousness.
A person can never obtain a righteous standing with God through his works. They are tainted, and the more religious a person gets, the more tainted they become. Self is at the center of them. Just consider the Pharisee in Luke 18:9-14.
When John the Baptist said, "He that believeth on the Son hath eternal life" (John 3:36), he wasn't talking about turning from sin and making Jesus Lord of your life. If that were the Gospel, then no one could be saved. Rather, John was talking about receiving the witness of Jesus as being true, because it contains the very words of God (John 3:32-34). And this witness is that "the Son of man came to save that which was lost" (Matthew 18:11, Luke 19:10) and "we have beheld and bear witness that the Father hath sent the Son to be the Saviour of the world" (1 John 4:14) and "God sent not the Son into the world to judge the world; but that the world should be saved through him" (John 3:17) and "I came not to judge the world, but to save the world" (John 12:47). Believing on the Son means believing His testimony that He is indeed your Savior.
You are a sinner. You cannot rehabilitate yourself. And even if God were to make you as holy as an archangel, that still wouldn't erase your past sins. And it still wouldn't meet God's standard of righteousness because "he putteth no trust in his servants; And his angels he chargeth with folly" (Job 4:18) and "he putteth no trust in his holy ones; Yea, the heavens are not clean in his sight" (Job 15:15). Repentance of sins, submission to Christ's lordship, transformation, evidence of fruitful living, and sanctification have no part in attaining the righteousness of God.
Have you been "justified freely by his grace" (Romans 3:24) or are you still looking within yourself? Have you believed in Jesus as your Savior, or are you still looking for evidence in your life?
Jesus said, "Verily, verily, I say unto you, He that believeth on me hath eternal life" (John 6:47). Do you believe him? Have you ever believed in Him as your Savior? If you have, then you can know for certain that you are saved and have eternal life. Your belief in Jesus as Savior is your evidence and it is the essence of your assurance.