The problem is that the muslims think that the Supreme whom they call Allah, is known to only them and that the Hindua are unaware of this Supreme Lord. This is their misconception. If they open the Hindu scriptures .. what to speak of opening any other scripture, if they simply read Bhagvad Gita once, they will realise that the scripture speaks of the Supreme duty of every living antity of the Supreme surrender to the Supreme Lord. It gives information about birth, death, the material world, the spiritual world, and the unmanifested and localised conception of the Supreme Lord. In other words, it contains everything. It contains all teh teachings of Koran. But unfortunately, without diving deep into this knowlege of science of soul, they already conclude that Hinduism is nothing but a bunch of followers following something suprestitious.
But this is not their fault. It is the fault of Hindus. Because 90% od Hindus today do not themselves know the real gem of knowledge contained in their scriptures. So in that way, Muslims are more devoted to the Supreme Lord, and the real followers of Sanatana dharma.