Do the conditions for a native disbeliever's entry into Islam differ from the conditions for an apostate's return to their religion?

There is no disagreement among scholars that if an original disbeliever utters the two declarations of faith (Shahadatayn), he is judged to have embraced Islam. However, if he utters only one of them without the other, it has been said that one is sufficient, and this is the madhhab (school of thought) of some Hanbalis. It has also been said that it is not sufficient unless both are uttered together, and this is the established view among the Hanbalis.

As for the apostate, if his apostasy was due to denying something known by necessity to be part of the religion, then merely uttering the two declarations of faith is not sufficient for him. Rather, he must affirm what he denied.