overrides the head because we feel that there is more to living than just our own survival, and being human means having compassion.
The heart helps us enjoy art, movies, songs, and literature. Often the connection to the heart involves stories. If we take the debate over the existence of God, out of the realm of science, where the head is the only part of us engaged, and place it in the context of a story, the heart will play a part.
The first story that explains the non-existence of God would be, "Once upon a time there was nothing. Something came from nothing and collided with something else. This collision brought about a set of events that has lead to us being here. We live and breathe because of random events. There is no purpose or cause. We are born and live and die until some other random event interrupts the cycle."
The second story that explains the existence of God is the essence of the Bible: "Once upon a time God created the earth and all that is in it. He created man with a free will to choose whether he wanted a relationship with God. Man could choose to obey God and bond with Him eternally. On the other hand, man could choose his own way, becoming his own god. Man chose to rebel against God. The result of his rebellion was the fall of creation. In the Garden of Eden, Adam and Eve lost Paradise. The evil serpent, Satan interrupted and tempted Eve to eat an apple from the tree that God had forbidden. God wanted to protect them from the full knowledge of evil that was inter-woven in the fibers of that Apple. Eve ate the apple and in its place struggle, disease, desolation, and ultimately death occurred. God loved his creation too much to let it collapse. God became man. Jesus lived a perfect life. He was executed by men because they could not bear the presence of God. Jesus was able to conquer death and rose again. He took the punishment for man's rebellion upon Himself. He is now able to offer a way back to a relationship with Himself for man. Just as man chose to become his own god, he can now choose to come back to a relationship with God.
This second story speaks to my heart. If faith helps us believe what we cannot see, for me, it takes MORE faith to believe the first story.