The arm is a metonym for the strength in the arm. Alternate translation: "strength like God's strength" (See: [[rc://en/ta/man/translate/figs-simile]])
This can be translated as a statement. Alternate translation: "You certainly cannot cause thunder with your voice the way God does with his." (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-metonymy]])