“One should try to find out what he is going to gain from the Bai'at and why it is necessary to enter into this pledge. Unless one knows what the advantage of a certain thing is and the value it possesses, one cannot appreciate it. It is just as there are various kinds of articles in the house: money-big and small coins-and wood etc. Everything is placed where it belongs, that is, everything will be cared for and looked after according to its value. Small coins will not receive the same care as the big ones. As for the pieces of wood, they will be thrown in a corner. In short, whatever will be a cause of bigger loss will be cared for more than other things. The most important point in Bai'at is Tauba (repentance)which means turning back. It indicates that condition in which man is closely connected with sin, and it is as if sins are the homeland and he is living in this habitation. Tauba means that he is now leaving this homeland. Turning back (Raju') means to adopt piety (to become pious).Leaving one's homeland is indeed a hard thing to do, and it entails thousands of hardships. When a man leaves his home, he feels it very much, then how much more one must be feeling while leaving one's homeland. He leaves every thing, his household belongings, his streets and his neighbours and bazaars (shops) and goes to another country.He does not come back to his old homeland.This is TAUBA.”

When a man is a sinner, his friends are different from those who are going to be his friends when he adopts Taqwa(fear of God).
The mystics have termed this change as 'death'.
Source: Malfoozat, Vol.1, p.2