repentance

All paths lead to me, none leads away I, the lightless, airless quarry Eagerly counting down to the day When at last my apportioned quarry Within my depths shall come to stay I, the vanquisher of the invincible The frustrator of every cunning schemer The fearless, the fearsome and the feared...

As salamu alaykum, Could the learned brothers explain the viewpoint of Ahlus Sunnah when it comes to repenting from kufr? The main questions I have are 1. Is it necessary to say the Shahadah to enter fold of Islam again? Or is simply doing tauba in the heart enough? 2. What can a person do...