What is the ruling on one who was extravagant in his sins and then repented?

Whoever repents to Allah with sincere repentance that fulfills its conditions, his repentance is accepted, no matter how great his sins; this is based on the Almighty's saying: "Say, 'O My servants who have transgressed against themselves [by committing sins], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" Allah has called disbelievers, polytheists, hypocrites, and sinners to repentance. It is not permissible to despair of Allah's mercy, for it is one of the major sins.