Oneness or Tawhid is considered as the most important pillar of Islam. A Muslim is expected to believe in Tawhid and all it's aspects. One can trace phrases related to Tawhid in Rig veda, the most ancient religious scripture of Hinduism, but it is just limited to the Tawhid of creation i.e The creator is one. When it comes to Tawhid of sustenance i.e The provider of sustenance is one, it fails to make this type of Tawhid clear. So as per Islamic terms, Hinduism cannot be considered as a religion of Monotheism.
Shaykh Kumail Rajani