To a Muslim, Allah is the Almighty, Creator and Sustainer of the universe, Who is similar to nothing and nothing is comparable to Him. God states in the Quran for those who make Him like His creation or vice versa:

There is nothing similar to Him.

―Quran 42:11

“…Muslims further recognize that Allah is beyond complete human understanding, as there is nothing in creation comparable to Him. Perhaps in the afterlife we will be gifted with greater understanding, but in this life, knowledge of our Creator is confined within the boundaries of revelation…”

-Source: Laurence B. Brown, MisGod’ed: A Roadmap Of Guidance And Misguidance In The Abrahamic Religions, pages 54–56 (PDF Version)