User blog comment:EmpyreanSmoke/Supernatural Q&A/@comment-95.112.161.208-20150915205700/@comment-24834479-20150916013415

God and the Archangels were able to lock the darkness away, but only if the mark is being willed by a living being. That was what was stopping the darkness from breaking free, so no, God couldn't just whip up magic armor and be safe from the Darkness.