Why does God address the believers with "O you who have believed" instead of "O you who have submitted"?

Because Islam (submission) can be a form of hypocrisy, Allah addressed His believing servants with "O you who have believed" (يا أيها الذين آمنوا) and not "O you who have submitted" (يا أيها الذين أسلموا). For the believer is alive through his faith, he hears and comprehends, unlike the dead disbeliever who neither hears nor comprehends.