﴿ لَا يَسْتَطِيعُونَ نَصْرَهُمْ وَهُمْ لَهُمْ جُندٌۭ مُّحْضَرُونَ ﴾

“they are unable to succour their devotees, even though to them they may [appear to] be hosts drawn up [for succour].”

They their gods cannot help them — they are being treated as though they were rational beings — and they their idol gods are their host as they claim their supporters ever-present but in the Fire together with them.