Sometimes you get a person, and you hope the person is converted. They make fairly rapid progress, and they can discuss the doctrines and understand them, perhaps very keen on doctrinal and theoretical information. Maybe they are also very good on apologetics, and can argue very strongly apologetically in the truth of the Christian religion, and the person and the work of Christ, but sometimes you are rather uncomfortable. There does not seem to be any heart. There does not seem to be any testimony of personal appreciation of Christ or grasp of him. You do not see the obvious signs that they actually walk with him, and are challenged by their own sin, and are striving in righteousness.
We see people who believe in Christ for the purpose of heaven and redemption, but you do not see any change in their lives. You do not see the sign of repentance in terms of turning away from the world, and cleaving to Christ and his values and his standards, following a pathway of holiness. You do not see change and commitment. Of course, Christ can tell. He is God. He has perfect insight and reads every heart. He will not trust himself to you. He won’t give you the blessings of conversion. He won’t give you his truth. He won’t be your Saviour, because he knows you. He knows you haven’t given your life to him. You haven’t forsaken the old life.