atheism

So I was with my family having dinner and the topic of religion came up. As we were arguing, you know the usual stuff, I brought as an example that if I some day were to tell them that I saw god would you believe me? They of course said no, and I told them why do you believe the first men that introduced religion (for my sake it was Islam).And you know what they replied with? "Well god sent that man , and I know that because he is the almighty and it was in his plans". I thought to myself that this is absolute craziness and that whatever you tell them they just won't understand and won't think otherwise. It's like they have closed their ears and won't hear anything else. Is it fear that's doing that or is it something else?