Is the repentance of one who said, "I have disavowed the religion of Islam," accepted, and is the principle "the certainty of Islam is not removed by the doubt of disbelief" adopted by the Shafi'is?

Repentance for a sin is accepted if it fulfills its conditions: desisting from the sin, regretting it, and resolving not to return to it. One who repents from a sin is like one who has no sin. The rule is that a Muslim is presumed to remain in their Islam and does not cease to be so except with certainty. The Shafi'is and others are cautious about excommunication (takfir) and condemn its expansion, as takfir is a grave danger, especially with the possibility of unintentionality.