What is the biblical basis for saying that unsaved souls are completely destroyed? (Annihilationism)

What is the biblical basis for saying that unsaved souls are completely destroyed? **Related Questions:** The following link covers the basis for saying that the unsaved are eternally punished, but not for the opposing claim that unsaved souls are destroyed: https://christianity.stackexchange.com/questions/968/what-is-the-biblical-basis-for-the-eternal-existence-of-the-lost-in-hell The following is also similar but asks why God didnt annihilate Adam and Eve (and hence eliminate future souls) when Adam fell: https://christianity.stackexchange.com/questions/32806/what-is-the-biblical-basis-for-saying-that-god-can-annihilate-human-souls