Is a single repentance sufficient for someone who has cursed the religion, or Allah, or the prophets, and then repented and uttered the two testimonies, or is it obligatory to repent from each statement separately? And what are the conditions for repentance for someone who committed major sins but forgot them during their repentance?

Cursing Allah or the Messenger is one of the gravest forms of apostasy, and scholars have ruled that the perpetrator should be killed. Whoever doubts their disbelief has disbelieved. However, if they regret and repent with a sincere repentance that fulfills all its conditions, Allah will accept their repentance. The repentance of an apostate is by embracing Islam and uttering the two testimonies of faith. If their apostasy was due to denying an obligatory act, then their repentance, in addition to the two testimonies, is to affirm that which they denied.

Repentance from all sins, in general, is sufficient, and a disbeliever's embrace of Islam erases all their misdeeds.