The Book of Mormon (1830) and the Pickthal translation of the Qur’an (1930), both completed long after “thee” and “thou” faded from common English usage, both adopted the archaic syntactical and grammatical forms used in the KJV. Why?
Here’s the Book of Mormon:
Holy, holy God; we believe that thou art God, and we believe that thou art holy, and that thou wast a spirit, and that thou art a spirit, and that thou wilt be a spirit forever. (Alma 31:15)
Here’s Pickthal’s translation of the first Surah:
In the name of Allah, the Beneficent, the Merciful. Praise be to Allah, Lord of the Worlds, The Beneficent, the Merciful. Master of the Day of Judgment, Thee (alone) we worship; Thee (alone) we ask for help. Show us the straight path, the path of those whom Thou hast favoured; not the (path) of those who earn Thine anger nor of those who go astray.
Of course, the old ASV (1901) did the same:
Who told thee that thou wast naked? Hast thou eaten of the tree, whereof I commanded thee that thou shouldest not eat? (Gen 3:11 ASV)
Why?