When people say in their hearts: "There is no God" they create a worldview of denial. Their mind is thinking about denying things as opposed to affirming things. They must feed this idea of their hearts with more and more negative things. They must continue to prove what "is not." They must continue to deny what "is." All of life becomes about denying, proving things wrong and putting things down.
Down is a fitting direction for such a heart.
However, when people believe in their hearts: There is a God and His Name is Father, Son and Holy Spirit, they create a worldview of affirmation. Their mind is thinking about affirming things. They get to feed this idea of their hearts with more and more positive things. They get to focus on what "is." All of life becomes one constant affirmation which they are receiving from God.
Up is a fitting direction for such a heart.
Does God exist? The answer determines the direction of your life.