A man cannot receive anything unless

"Nobody has any power unless"

it has been given to him from heaven

Here "heaven" is used as a metonym to refer to God. This can be stated in an active form. Alternate translation: "God has given it to him" (See: rc://en/ta/man/jit/figs-metonymy and rc://en/ta/man/jit/figs-activepassive)