What is the ruling on repeatedly repenting from major sins and then relapsing into them due to negligence or weakness? Does repentance erase previous sins? And does Allah accept the repentance of one who was an unbeliever, committed immoral acts, and neither fasted nor prayed, and how are prayers and fasting to be made up in this case?

Allah Almighty is the Most Merciful of those who show mercy. He accepts the repentance of those who repent and forgives those who seek His forgiveness. If a servant commits a sin and then repents with sincere repentance and the intention not to return to it, Allah will forgive him, even if the sin and repentance are repeated. Repentance is an obligation upon every Muslim, and it is aided by supplication, keeping company with the righteous, and avoiding bad companions.