The idea of letting your feelings make big decisions is crazy. A scientist couldn't get his new medication pass the FDA by only saying, "I know in my heart that his medication will work great and isn't dangerous." The FDA would ask for evidence to back up this statement. A lawyer couldn't free his client by simply stating, "I know my client is not guilty because I can feel it in my heart." The judge, like the FDA in the previous example, would also require evidence. Our lives should be based on evidence not the warm and fuzzy feelings that we experience.
When the Bible was written people didn't know much about the brain which is why the Bible is filled with the idea that you think and believe things with your heart. This lack of knowledge has also lead to phrases like "I love you with all of my heart" to be part of our language. An all knowing god would have known about the brain and would not have misled his followers about the body he created. Although, there are so many things wrong with our bodies I can see why an all-powerful god wouldn't want to brag.
I know that many Christians say that everything around us proves God exists. However, through scientific discoveries we can explain how our earth came to be and shows that God isn't necessary for any of it. I know this doesn't mean that we can say with 100% certainty that there is not a god. However, there is enough evidence to feel comfortable living as if there isn't. Just as Christians live as if the all the other gods don't exist.
"I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours" -- Stephen Roberts