What is the ruling on one who disbelieves, then immediately repents, pronounces the Shahada, and turns back to Allah?

Allah Almighty has opened the door of repentance to everyone who sincerely desires it, even if it is from disbelief, as long as the one repenting has not reached the death rattle. So, if a person who said or did something that expels him from the fold of Islam repents with a repentance that fulfills its conditions, then that is sufficient to expiate his sin.