The age of the Universe tells us that the Universe had a beginning. So the Universe that began to exist either must have created itself or must have been created by 'something'. Since, something cannot create itself, the Universe must have been created by 'something'. We call this 'something' as God.
We have different words for “God” in different languages. In the Arabic language, we refer to God as “Allah”. When the Muslims utter the word “Allah”, they are not referring to their personal God, but rather they are referring to God who created all of us and all that exists.
The Universe would never have come into existence, if there was a disagreement between different gods regarding the creation of the Universe. The existence of this universe and the perfect order we observe in it, is an undeniable and irrefutable proof that there is only One Supreme God, who is managing and regulating all its affairs.
Hindus, Muslims and people of all faiths have the same Criminal law. Like Muslims, each religion has their own personal laws. Hindus have Hindu Personal Law which is based on their religious scriptures like Vedas, Smritis, and Upanishads.