There are many religious books of Hinduism but none of them is unanimously followed by all hindus in the world. Some follow Vedas whiel others follow maha baharat and some follow puranas. Thus we do not find a single hindu who follows or accepts all hindu sacred books as true and from god.
In fact, hindus believe that there sacred books have been written by rishees who were sent by god or were the pious men of god. These rishis wrote more than 12 vedas but others were lost and only 12 are remaining. There are claims from hindus that Vedas are the only texts which are not corrupted but all others are corrupted. The concept of one true god is remained only in Vedas today. No other book purely promotes the idea of one god but Vedas. This is the same book which rejects the hindu dislikness for non veg. and its dislikeness for animal sacrifice.
There are several places in Vedas where god is described as only one who cannot be imagined. For example;
“Verily He is one
Single, indivisible, supreme reality. “
- Atharva Veda 13/4/20
This vedic verse shows that the gods of hindus is one who cannot be divided or cannot be two or three or 33 caror. Similarly in another verse the concept of god is described as;
“He is the sole sovereign
Of the universe. “
- Rig Veda 6/36/4
How can hindus then deny the sole sovereign status of their god? They jump and deny when they are told that god is one, they connect everything which contains oneness of god to brahma which is their ultimate god but they reject that their god is actually one. In another vadic verse this concept is again described clearly;
He is one, unparalleled
Through His wondrous, mighty
And formidable laws and deeds.
- Rig Veda 8/1/27
This verse says that the god of hindus is unique who is not like anyone else. This means, the gods hindus worship are not gods at all. They are some fiction characters who had no reality.
In another verse of veda we learn yet another attribute of the god of the hindus.
“There is only One
Who ought to be adored
By the people. “
- Atharva Veda 2/2/1
There are many other verses from Vedas which show that the god of hindus is none other than the god of muslims i.e. ALLAH. Vedas are said to be the oldest scripture on earth. we do not have any authenticative measures to verify the age of Vedas but with utmost surety we can say that the god which hindus used to worship was one god later on they deviated from the right path and kept on worshiping idols.