How do we know that Allah SWT exists? The first and foremost requirement for a person to become a Muslim is to believe whole-heartedly that Allah SWT exists. Allah SWT, the one and only God. Nevertheless, He cannot be seen by a human-or any living creature, for that matter. In simpler words, Allah SWT is invisible. He was, is, and will be invisible for the rest the world's existence until the day when the universe comes to and end.
