The exact way to tell is that people not accepting god’s facts because people asumes what they see ,hearing and believing it.
For example in hindu religion GOD is been described as universe in the first half of epic period by the people living in the age of starting from lord murugar avathar to the great epic mahabaratha .
But later after that during the reign of cholas GOD is been described as shapefull creature and not as paramathma as universe ..where the proof lies in the temple which they built.this is all due to brain thoughts
When coming to existence of god whether it is true or not is to analyse only the epic portion where the people believe only in good happenings like cultivating self desciplined which helped them to out come the suffering of painfull death created by themselves ( Sufferings are created by us due to our adamancy ,innocence,violence etc). That self desciplined comes from experience soul which is called as god,that is why god is called as universe.we must think like this ,but if you start researching on god of how he looks and who he is then we are the biggest fools.
A very simple concept is that,. it is not the religion or the way we pray or the way we believe which makes us to reach god or believe god,it is the character and the way which we think and see and choose to reached god.