In Hindu philosophy creation, preservation and destruction are considered as three natures of God forming the core concept of Hindu trinity. When Oppenheimer uttered "Now I am become death, destroyer of worlds", the verse was referring to the same thing.
First of all Oppenheimer was misquoting the Bhagwat Gita. The original sentence is ,
Kalo smi lokkaya krt pravrddho, lokan samahartum iha pravrttah,
rte pitvam na bhavisyanti, sarve ye vasthitah pratyanikesu yodhah,
Translates as,
I am the terrible destroyer
Time, engaged in destroying all beings in this world,
even without you none will be spared in the future, of all those warriors in the opposing army.
It means that only Time is eternal an our death is confirmed. So best not to worry about the result and do your karma, since we will all die in the end. It is to teach us not to hesistate in killing others for dharma,
in a war fought for the protection of Dharma. Even if you do not kill others, they will anyway die, but Dharma will not be protected or served.