According to shamkracharya,There are three levels of reality
The rope-snake illusion or the state of the dream appears to be real only at the illusory level, but are refuted at the empirical level. Again, the empirical level is the experience of the wakeful state such as to know the rope as rope. This level of reality is collective and comparatively more durable than illusory level, but it is still refuted at the transcendental level. The transcendental level of reality is irrefutable in all the times and hence, Brahman is the only uncontradicted reality.
One can easily reach the illusory level to empirical level just by waking up however moving to transcendental level from empirical level require a long devotion.At the empirical level one can not surmise Braham because it is attributeless,shapeless and omnipresent. To get liberation from worldly affair and merge into brahmn a process needs to be followed.
So God as the creator is only apparent. Yet, his importance and value should not be ignored. It is only through the lower standpoint that we can gradually mount up to the higher. Shankaracharya believes in the gradual revelation of truth. Thus, at the first level, the world alone is real. At the second, world and God and at the last, only God. This last state is absolute monism of Shankaracharya. He, therefore, believes in the utility of worshipping God because this purifies the heart and prepares one for gradually reaching the highest view.
Hinduism gives freedom to worshiper to worship any object of the world at an empirical level. as a result, Hindu people worship a tree, animal, idols,33 crore gods etc. Hindusim believed in polytheism at the empirical level. At trancedental level, all god is one I .e.Brahmn