Is Oppenheimer's quote "I am become death" grammatically correct? [duplicate]

After J. Robert Oppenheimer made his discoveries of nuclear energy, he said a quote from Bhagavad-Gita, it goes as follows

I am become death, the destroyer of worlds.

Is this proper English?

As Dan Bron says in his comment, it is proper archaic English, which is familiar to many English speakers through having read parts of the King James translation on the bible, which goes back to an earlier variety of English, Elizabethan English, when the perfect auxiliary verb "be" was used with verbs of motion, instead of the "have" in modern English.

Oppenheimer, as well as being the premier nuclear physicist of his day, was a student of the classical languages, including Sanskrit. Here, doubtless quite deliberately, he uses the archaic perfect form in imitation of that found in the KJ Bible, or possibly to invoke a traditional rendering in English of some passage in the Bhagavad Gita.