مَا نَعْبُدُهُمْ إِلَّا لِيُقَرِّبُونَا إِلَى اللَّهِ زُلْفَىٰ. (al-Zumar 39:3)
We worship them only so that they may bring us nearer to Allah.
The idolaters' words state their intended purpose: making idols intermediaries to obtain nearness to Allah.
Inventing such comparisons about Allah can lead to false belief and worship. This is why comparisons formed on one's own authority are prohibited.