The following words of quran will clarify your doubts against apostasy. If still it is not clear to you then you donot want to understand it. there is no compulsion to religion in Islam but at the same time a muslim has to convey the message of allah to non belivers but not by sword but by your deed and behaviour.
Sword is only allowed to be used at the time of war. And the war should be to protect yourself and not just for the sake of fighting.
%u201CLet there be no compulsion in religion: Truth stands out clear from error%u201D [Al-Qur%u2019an 2:256]
