I know that nothing is similar to Allah (Surah Al - Ikhlas). But human nature wants to visualize what it is worshiping.
In Salah ihsan means worshiping Allah as if you are seeing him because even though you don't see him, he sees you. If someone during worship were to imagine Allah in the shape of a mighty and beautiful being that has a very strong and beautiful light and is astonishingly big and mighty and beautiful.
My question is: Would he commit major kufr even though he had only the good intention of giving a mighty image in his imagination to the being he is worshiping?
There is also a famous hadith about Isra and Mi'raj where they ask the prophet s.a.w. Did you see Allah. He s.a.w replies: What could I see. There was only light.