It has nothing to do with the belief in God.
One can be a Hindu and remain an Atheist ,like Carvakas, Buddhist,Ajivaka.
These are totally opposed to Vedas and deny their authority.
Orthodox systems are those which belive in the Authoroty of the Vedas.
Those, like Jainism are called Heterodox and they do not believe in the Vedas.
Even among the Orthodox systems which believe in the authority of the Vedas deny God, like The Nyaya System.
The difference between Mantras and the other two Types is that Mantras deliver guaranteed results, if one follows the procedures laid down.
Whereas in the case of Stotra or Parayana,the Divine intervention is left to the pleasure of the God addressed to, in the case of Mantras, the Gods are obliged to grant the requests as they represent the essence of Reality and in fact the Form of Gods themselves.
That is why even A Raskshasa can deliver a Brahmastra by invoking a Mantra.
More to follow on the scientific explanation of Mantras, their validity analysis by Spectroscopy,Cymatics
‘So, He could have invented sanitary Napkins!’
I did not respond to this comment.
The point is that we have to let it be known our treasures with authority, which was eroded by the British as they have done for the whole world, including their own Irish.
I will take personal insults.
People have reported being enveloped in a sheet of white light which felt warm, they have been able to see what is taking place, though they could not perceive, see or hear it with their senses.
The perception has become more acute.
The flip side of this is that the Charvaka’s first Text,the primary source, which is lost to us , is credited to Bruhaspati, the Guru,Preceptor of the Devas!