thank you brother Rafi for you response;
What i have understood is that Allah has its system through which this world is moving abiding by the pre-set rules.
Whereas Dua is concerned, its our wishes for which we have to effort and through Allah's built-in system we are responded and our prayers answered, so it is his system through which we fulfilled our desires/wishes and also know about Allah existence;
At this point one would question if system is to be followed what is the role of Allah despite it is his set of rules i.e., an atheist. and other say these thoughts only makes you away from Allah......
Thank in anticipation.